feat: add display UI with splash screen, dashboard, and RSSI sparkline

Implement full SSD1306 OLED display support:
- Splash screen on boot (1.5s) with project name, version, board
- Dashboard showing radio state, config, counters, RSSI/SNR
- RSSI history sparkline (64-sample ring buffer, 2px-wide bars)
- DisplayOn/DisplayOff host commands routed via dedicated channel
- Pure render functions against generic DrawTarget (no hardware coupling)
- Display on/off control bypasses radio task entirely

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

vendor/indexmap/src/inner/entry.rs

@@ -0,0 +1,398 @@
+use super::{equivalent, get_hash, Bucket, Core};
+use crate::map::{Entry, IndexedEntry};
+use crate::HashValue;
+use core::cmp::Ordering;
+use core::mem;
+
+impl<'a, K, V> Entry<'a, K, V> {
+    pub(crate) fn new(map: &'a mut Core<K, V>, hash: HashValue, key: K) -> Self
+    where
+        K: Eq,
+    {
+        let eq = equivalent(&key, &map.entries);
+        match map.indices.find_entry(hash.get(), eq) {
+            Ok(entry) => Entry::Occupied(OccupiedEntry {
+                bucket: entry.bucket_index(),
+                index: *entry.get(),
+                map,
+            }),
+            Err(_) => Entry::Vacant(VacantEntry { map, hash, key }),
+        }
+    }
+}
+
+/// A view into an occupied entry in an [`IndexMap`][crate::IndexMap].
+/// It is part of the [`Entry`] enum.
+pub struct OccupiedEntry<'a, K, V> {
+    map: &'a mut Core<K, V>,
+    // We have a mutable reference to the map, which keeps these two
+    // indices valid and pointing to the correct entry.
+    index: usize,
+    bucket: usize,
+}
+
+impl<'a, K, V> OccupiedEntry<'a, K, V> {
+    /// Constructor for `RawEntryMut::from_hash`
+    pub(crate) fn from_hash<F>(
+        map: &'a mut Core<K, V>,
+        hash: HashValue,
+        mut is_match: F,
+    ) -> Result<Self, &'a mut Core<K, V>>
+    where
+        F: FnMut(&K) -> bool,
+    {
+        let entries = &*map.entries;
+        let eq = move |&i: &usize| is_match(&entries[i].key);
+        match map.indices.find_entry(hash.get(), eq) {
+            Ok(entry) => Ok(OccupiedEntry {
+                bucket: entry.bucket_index(),
+                index: *entry.get(),
+                map,
+            }),
+            Err(_) => Err(map),
+        }
+    }
+
+    pub(crate) fn into_core(self) -> &'a mut Core<K, V> {
+        self.map
+    }
+
+    pub(crate) fn get_bucket(&self) -> &Bucket<K, V> {
+        &self.map.entries[self.index]
+    }
+
+    pub(crate) fn get_bucket_mut(&mut self) -> &mut Bucket<K, V> {
+        &mut self.map.entries[self.index]
+    }
+
+    pub(crate) fn into_bucket(self) -> &'a mut Bucket<K, V> {
+        &mut self.map.entries[self.index]
+    }
+
+    /// Return the index of the key-value pair
+    #[inline]
+    pub fn index(&self) -> usize {
+        self.index
+    }
+
+    /// Gets a reference to the entry's key in the map.
+    ///
+    /// Note that this is not the key that was used to find the entry. There may be an observable
+    /// difference if the key type has any distinguishing features outside of `Hash` and `Eq`, like
+    /// extra fields or the memory address of an allocation.
+    pub fn key(&self) -> &K {
+        &self.get_bucket().key
+    }
+
+    /// Gets a reference to the entry's value in the map.
+    pub fn get(&self) -> &V {
+        &self.get_bucket().value
+    }
+
+    /// Gets a mutable reference to the entry's value in the map.
+    ///
+    /// If you need a reference which may outlive the destruction of the
+    /// [`Entry`] value, see [`into_mut`][Self::into_mut].
+    pub fn get_mut(&mut self) -> &mut V {
+        &mut self.get_bucket_mut().value
+    }
+
+    /// Converts into a mutable reference to the entry's value in the map,
+    /// with a lifetime bound to the map itself.
+    pub fn into_mut(self) -> &'a mut V {
+        &mut self.into_bucket().value
+    }
+
+    /// Sets the value of the entry to `value`, and returns the entry's old value.
+    pub fn insert(&mut self, value: V) -> V {
+        mem::replace(self.get_mut(), value)
+    }
+
+    /// Remove the key, value pair stored in the map for this entry, and return the value.
+    ///
+    /// **NOTE:** This is equivalent to [`.swap_remove()`][Self::swap_remove], replacing this
+    /// entry's position with the last element, and it is deprecated in favor of calling that
+    /// explicitly. If you need to preserve the relative order of the keys in the map, use
+    /// [`.shift_remove()`][Self::shift_remove] instead.
+    #[deprecated(note = "`remove` disrupts the map order -- \
+        use `swap_remove` or `shift_remove` for explicit behavior.")]
+    pub fn remove(self) -> V {
+        self.swap_remove()
+    }
+
+    /// Remove the key, value pair stored in the map for this entry, and return the value.
+    ///
+    /// Like [`Vec::swap_remove`][alloc::vec::Vec::swap_remove], the pair is removed by swapping it
+    /// with the last element of the map and popping it off.
+    /// **This perturbs the position of what used to be the last element!**
+    ///
+    /// Computes in **O(1)** time (average).
+    pub fn swap_remove(self) -> V {
+        self.swap_remove_entry().1
+    }
+
+    /// Remove the key, value pair stored in the map for this entry, and return the value.
+    ///
+    /// Like [`Vec::remove`][alloc::vec::Vec::remove], the pair is removed by shifting all of the
+    /// elements that follow it, preserving their relative order.
+    /// **This perturbs the index of all of those elements!**
+    ///
+    /// Computes in **O(n)** time (average).
+    pub fn shift_remove(self) -> V {
+        self.shift_remove_entry().1
+    }
+
+    /// Remove and return the key, value pair stored in the map for this entry
+    ///
+    /// **NOTE:** This is equivalent to [`.swap_remove_entry()`][Self::swap_remove_entry],
+    /// replacing this entry's position with the last element, and it is deprecated in favor of
+    /// calling that explicitly. If you need to preserve the relative order of the keys in the map,
+    /// use [`.shift_remove_entry()`][Self::shift_remove_entry] instead.
+    #[deprecated(note = "`remove_entry` disrupts the map order -- \
+        use `swap_remove_entry` or `shift_remove_entry` for explicit behavior.")]
+    pub fn remove_entry(self) -> (K, V) {
+        self.swap_remove_entry()
+    }
+
+    /// Remove and return the key, value pair stored in the map for this entry
+    ///
+    /// Like [`Vec::swap_remove`][alloc::vec::Vec::swap_remove], the pair is removed by swapping it
+    /// with the last element of the map and popping it off.
+    /// **This perturbs the position of what used to be the last element!**
+    ///
+    /// Computes in **O(1)** time (average).
+    pub fn swap_remove_entry(mut self) -> (K, V) {
+        self.remove_index();
+        self.map.swap_remove_finish(self.index)
+    }
+
+    /// Remove and return the key, value pair stored in the map for this entry
+    ///
+    /// Like [`Vec::remove`][alloc::vec::Vec::remove], the pair is removed by shifting all of the
+    /// elements that follow it, preserving their relative order.
+    /// **This perturbs the index of all of those elements!**
+    ///
+    /// Computes in **O(n)** time (average).
+    pub fn shift_remove_entry(mut self) -> (K, V) {
+        self.remove_index();
+        self.map.shift_remove_finish(self.index)
+    }
+
+    fn remove_index(&mut self) {
+        let entry = self.map.indices.get_bucket_entry(self.bucket).unwrap();
+        debug_assert_eq!(*entry.get(), self.index);
+        entry.remove();
+    }
+
+    /// Moves the position of the entry to a new index
+    /// by shifting all other entries in-between.
+    ///
+    /// This is equivalent to [`IndexMap::move_index`][`crate::IndexMap::move_index`]
+    /// coming `from` the current [`.index()`][Self::index].
+    ///
+    /// * If `self.index() < to`, the other pairs will shift down while the targeted pair moves up.
+    /// * If `self.index() > to`, the other pairs will shift up while the targeted pair moves down.
+    ///
+    /// ***Panics*** if `to` is out of bounds.
+    ///
+    /// Computes in **O(n)** time (average).
+    #[track_caller]
+    pub fn move_index(self, to: usize) {
+        if self.index != to {
+            let _ = self.map.entries[to]; // explicit bounds check
+            self.map.move_index_inner(self.index, to);
+            self.update_index(to);
+        }
+    }
+
+    /// Swaps the position of entry with another.
+    ///
+    /// This is equivalent to [`IndexMap::swap_indices`][`crate::IndexMap::swap_indices`]
+    /// with the current [`.index()`][Self::index] as one of the two being swapped.
+    ///
+    /// ***Panics*** if the `other` index is out of bounds.
+    ///
+    /// Computes in **O(1)** time (average).
+    #[track_caller]
+    pub fn swap_indices(self, other: usize) {
+        if self.index != other {
+            // Since we already know where our bucket is, we only need to find the other.
+            let hash = self.map.entries[other].hash;
+            let other_mut = self.map.indices.find_mut(hash.get(), move |&i| i == other);
+            *other_mut.expect("index not found") = self.index;
+
+            self.map.entries.swap(self.index, other);
+            self.update_index(other);
+        }
+    }
+
+    fn update_index(self, to: usize) {
+        let index = self.map.indices.get_bucket_mut(self.bucket).unwrap();
+        debug_assert_eq!(*index, self.index);
+        *index = to;
+    }
+}
+
+impl<'a, K, V> From<IndexedEntry<'a, K, V>> for OccupiedEntry<'a, K, V> {
+    fn from(other: IndexedEntry<'a, K, V>) -> Self {
+        let index = other.index();
+        let map = other.into_core();
+        let hash = map.entries[index].hash;
+        let bucket = map
+            .indices
+            .find_bucket_index(hash.get(), move |&i| i == index)
+            .expect("index not found");
+        Self { map, index, bucket }
+    }
+}
+
+/// A view into a vacant entry in an [`IndexMap`][crate::IndexMap].
+/// It is part of the [`Entry`] enum.
+pub struct VacantEntry<'a, K, V> {
+    map: &'a mut Core<K, V>,
+    hash: HashValue,
+    key: K,
+}
+
+impl<'a, K, V> VacantEntry<'a, K, V> {
+    /// Return the index where a key-value pair may be inserted.
+    pub fn index(&self) -> usize {
+        self.map.indices.len()
+    }
+
+    /// Gets a reference to the key that was used to find the entry.
+    pub fn key(&self) -> &K {
+        &self.key
+    }
+
+    pub(crate) fn key_mut(&mut self) -> &mut K {
+        &mut self.key
+    }
+
+    /// Takes ownership of the key, leaving the entry vacant.
+    pub fn into_key(self) -> K {
+        self.key
+    }
+
+    /// Inserts the entry's key and the given value into the map, and returns a mutable reference
+    /// to the value.
+    ///
+    /// Computes in **O(1)** time (amortized average).
+    pub fn insert(self, value: V) -> &'a mut V {
+        let Self { map, hash, key } = self;
+        map.insert_unique(hash, key, value).value_mut()
+    }
+
+    /// Inserts the entry's key and the given value into the map, and returns an `OccupiedEntry`.
+    ///
+    /// Computes in **O(1)** time (amortized average).
+    pub fn insert_entry(self, value: V) -> OccupiedEntry<'a, K, V> {
+        let Self { map, hash, key } = self;
+        let index = map.indices.len();
+        debug_assert_eq!(index, map.entries.len());
+        let bucket = map
+            .indices
+            .insert_unique(hash.get(), index, get_hash(&map.entries))
+            .bucket_index();
+        map.push_entry(hash, key, value);
+        OccupiedEntry { map, index, bucket }
+    }
+
+    /// Inserts the entry's key and the given value into the map at its ordered
+    /// position among sorted keys, and returns the new index and a mutable
+    /// reference to the value.
+    ///
+    /// If the existing keys are **not** already sorted, then the insertion
+    /// index is unspecified (like [`slice::binary_search`]), but the key-value
+    /// pair is inserted at that position regardless.
+    ///
+    /// Computes in **O(n)** time (average).
+    pub fn insert_sorted(self, value: V) -> (usize, &'a mut V)
+    where
+        K: Ord,
+    {
+        let slice = crate::map::Slice::from_slice(&self.map.entries);
+        let i = slice.binary_search_keys(&self.key).unwrap_err();
+        (i, self.shift_insert(i, value))
+    }
+
+    /// Inserts the entry's key and the given value into the map at its ordered
+    /// position among keys sorted by `cmp`, and returns the new index and a
+    /// mutable reference to the value.
+    ///
+    /// If the existing keys are **not** already sorted, then the insertion
+    /// index is unspecified (like [`slice::binary_search`]), but the key-value
+    /// pair is inserted at that position regardless.
+    ///
+    /// Computes in **O(n)** time (average).
+    pub fn insert_sorted_by<F>(self, value: V, mut cmp: F) -> (usize, &'a mut V)
+    where
+        F: FnMut(&K, &V, &K, &V) -> Ordering,
+    {
+        let slice = crate::map::Slice::from_slice(&self.map.entries);
+        let (Ok(i) | Err(i)) = slice.binary_search_by(|k, v| cmp(k, v, &self.key, &value));
+        (i, self.shift_insert(i, value))
+    }
+
+    /// Inserts the entry's key and the given value into the map at its ordered
+    /// position using a sort-key extraction function, and returns the new index
+    /// and a mutable reference to the value.
+    ///
+    /// If the existing keys are **not** already sorted, then the insertion
+    /// index is unspecified (like [`slice::binary_search`]), but the key-value
+    /// pair is inserted at that position regardless.
+    ///
+    /// Computes in **O(n)** time (average).
+    pub fn insert_sorted_by_key<B, F>(self, value: V, mut sort_key: F) -> (usize, &'a mut V)
+    where
+        B: Ord,
+        F: FnMut(&K, &V) -> B,
+    {
+        let search_key = sort_key(&self.key, &value);
+        let slice = crate::map::Slice::from_slice(&self.map.entries);
+        let (Ok(i) | Err(i)) = slice.binary_search_by_key(&search_key, sort_key);
+        (i, self.shift_insert(i, value))
+    }
+
+    /// Inserts the entry's key and the given value into the map at the given index,
+    /// shifting others to the right, and returns a mutable reference to the value.
+    ///
+    /// ***Panics*** if `index` is out of bounds.
+    ///
+    /// Computes in **O(n)** time (average).
+    #[track_caller]
+    pub fn shift_insert(self, index: usize, value: V) -> &'a mut V {
+        self.map
+            .shift_insert_unique(index, self.hash, self.key, value)
+            .value_mut()
+    }
+
+    /// Replaces the key at the given index with this entry's key, returning the
+    /// old key and an `OccupiedEntry` for that index.
+    ///
+    /// ***Panics*** if `index` is out of bounds.
+    ///
+    /// Computes in **O(1)** time (average).
+    #[track_caller]
+    pub fn replace_index(self, index: usize) -> (K, OccupiedEntry<'a, K, V>) {
+        let Self { map, hash, key } = self;
+
+        // NB: This removal and insertion isn't "no grow" (with unreachable hasher)
+        // because hashbrown's tombstones might force a resize anyway.
+        let old_hash = map.entries[index].hash;
+        map.indices
+            .find_entry(old_hash.get(), move |&i| i == index)
+            .expect("index not found")
+            .remove();
+        let bucket = map
+            .indices
+            .insert_unique(hash.get(), index, get_hash(&map.entries))
+            .bucket_index();
+
+        let entry = &mut map.entries[index];
+        entry.hash = hash;
+        let old_key = mem::replace(&mut entry.key, key);
+
+        (old_key, OccupiedEntry { map, index, bucket })
+    }
+}

vendor/indexmap/src/inner/extract.rs

@@ -0,0 +1,108 @@
+#![allow(unsafe_code)]
+
+use super::{Bucket, Core};
+use crate::util::simplify_range;
+
+use core::ops::RangeBounds;
+
+impl<K, V> Core<K, V> {
+    #[track_caller]
+    pub(crate) fn extract<R>(&mut self, range: R) -> ExtractCore<'_, K, V>
+    where
+        R: RangeBounds<usize>,
+    {
+        let range = simplify_range(range, self.entries.len());
+
+        // SAFETY: We must have consistent lengths to start, so that's a hard assertion.
+        // Then the worst `set_len` can do is leak items if `ExtractCore` doesn't drop.
+        assert_eq!(self.entries.len(), self.indices.len());
+        unsafe {
+            self.entries.set_len(range.start);
+        }
+        ExtractCore {
+            map: self,
+            new_len: range.start,
+            current: range.start,
+            end: range.end,
+        }
+    }
+}
+
+pub(crate) struct ExtractCore<'a, K, V> {
+    map: &'a mut Core<K, V>,
+    new_len: usize,
+    current: usize,
+    end: usize,
+}
+
+impl<K, V> Drop for ExtractCore<'_, K, V> {
+    fn drop(&mut self) {
+        let old_len = self.map.indices.len();
+        let mut new_len = self.new_len;
+
+        debug_assert!(new_len <= self.current);
+        debug_assert!(self.current <= self.end);
+        debug_assert!(self.current <= old_len);
+        debug_assert!(old_len <= self.map.entries.capacity());
+
+        // SAFETY: We assume `new_len` and `current` were correctly maintained by the iterator.
+        // So `entries[new_len..current]` were extracted, but the rest before and after are valid.
+        unsafe {
+            if new_len == self.current {
+                // Nothing was extracted, so any remaining items can be left in place.
+                new_len = old_len;
+            } else if self.current < old_len {
+                // Need to shift the remaining items down.
+                let tail_len = old_len - self.current;
+                let base = self.map.entries.as_mut_ptr();
+                let src = base.add(self.current);
+                let dest = base.add(new_len);
+                src.copy_to(dest, tail_len);
+                new_len += tail_len;
+            }
+            self.map.entries.set_len(new_len);
+        }
+
+        if new_len != old_len {
+            // We don't keep track of *which* items were extracted, so reindex everything.
+            self.map.rebuild_hash_table();
+        }
+    }
+}
+
+impl<K, V> ExtractCore<'_, K, V> {
+    pub(crate) fn extract_if<F>(&mut self, mut pred: F) -> Option<Bucket<K, V>>
+    where
+        F: FnMut(&mut Bucket<K, V>) -> bool,
+    {
+        debug_assert!(self.end <= self.map.entries.capacity());
+
+        let base = self.map.entries.as_mut_ptr();
+        while self.current < self.end {
+            // SAFETY: We're maintaining both indices within bounds of the original entries, so
+            // 0..new_len and current..indices.len() are always valid items for our Drop to keep.
+            unsafe {
+                let item = base.add(self.current);
+                if pred(&mut *item) {
+                    // Extract it!
+                    self.current += 1;
+                    return Some(item.read());
+                } else {
+                    // Keep it, shifting it down if needed.
+                    if self.new_len != self.current {
+                        debug_assert!(self.new_len < self.current);
+                        let dest = base.add(self.new_len);
+                        item.copy_to_nonoverlapping(dest, 1);
+                    }
+                    self.current += 1;
+                    self.new_len += 1;
+                }
+            }
+        }
+        None
+    }
+
+    pub(crate) fn remaining(&self) -> usize {
+        self.end - self.current
+    }
+}