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/encode_unicode/tests/oks.rs

@@ -0,0 +1,284 @@
+/* Copyright 2016 The encode_unicode Developers
+ *
+ * Licensed under the Apache License, Version 2.0, <LICENSE-APACHE or
+ * http://apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or
+ * http://opensource.org/licenses/MIT>, at your option. This file may not be
+ * copied, modified, or distributed except according to those terms.
+ */
+
+//! Test that every method gives the correct result for valid values.
+//! Except iterators, which are stateful.
+
+use std::char;
+use std::str::{self,FromStr};
+use std::cmp::Ordering;
+use std::hash::{Hash,Hasher};
+use std::collections::hash_map::DefaultHasher;
+#[allow(deprecated,unused)]
+use std::ascii::AsciiExt;
+use std::iter::FromIterator;
+extern crate encode_unicode;
+use encode_unicode::*;
+
+
+#[test]
+fn equal_defaults() {
+    assert_eq!(Utf8Char::default().to_char(), char::default());
+    assert_eq!(Utf16Char::default().to_char(), char::default());
+}
+
+#[test]
+fn same_size_as_char() {
+    use std::mem::size_of;
+    assert_eq!(size_of::<Utf8Char>(), size_of::<char>());
+    assert_eq!(size_of::<Utf16Char>(), size_of::<char>());
+}
+
+#[test]
+fn utf16chars_to_string() {
+    let s = "aå\u{10ffff}‽\u{100000}\u{fee1}";
+    let u16cs = s.chars().map(|c| Utf16Char::from(c) ).collect::<Vec<Utf16Char>>();
+
+    let mut from_refs: String = u16cs.iter().collect();
+    assert_eq!(&from_refs, s);
+    from_refs.extend(&u16cs);
+    assert_eq!(&from_refs[s.len()..], s);
+
+    let mut from_vals: String = u16cs.iter().cloned().collect();
+    assert_eq!(&from_vals, s);
+    from_vals.extend(u16cs);
+    assert_eq!(&from_vals[s.len()..], s);
+}
+
+
+const EDGES_AND_BETWEEN: [char;19] = [
+    '\u{0}',// min
+    '\u{3b}',// middle ASCII
+    'A',// min ASCII uppercase
+    'N',// middle ASCII uppercase
+    'Z',// max ASCII uppercase
+    'a',// min ASCII lowercase
+    'm',// middle ASCII lowercase
+    'z',// max ASCII lowercase
+    '\u{7f}',// max ASCII and 1-byte UTF-8
+    '\u{80}',// min 2-byte UTF-8
+    '\u{111}',// middle
+    '\u{7ff}',// max 2-byte UTF-8
+    '\u{800}',// min 3-byte UTF-8
+    '\u{d7ff}',// before reserved
+    '\u{e000}',// after reserved
+    '\u{ffff}',// max UTF-16 single and 3-byte UTF-8
+    '\u{10000}',// min UTF-16 surrogate and 4-byte UTF-8
+    '\u{abcde}',// middle
+    '\u{10ffff}',// max
+];
+
+fn eq_cmp_hash(c: char) -> (Utf8Char, Utf16Char) {
+    fn hash<T:Hash>(v: T) -> u64 {
+        #[allow(deprecated)]
+        let mut hasher = DefaultHasher::new();
+        v.hash(&mut hasher);
+        hasher.finish()
+    }
+    let u8c = c.to_utf8();
+    assert_eq!(u8c.to_char(), c);
+    assert_eq!(u8c, u8c);
+    assert_eq!(hash(u8c), hash(u8c));
+    assert_eq!(u8c.cmp(&u8c), Ordering::Equal);
+    assert!(u8c.eq_ignore_ascii_case(&u8c));
+    let u16c = c.to_utf16();
+    assert_eq!(u16c.to_char(), c);
+    assert_eq!(u16c, u16c);
+    assert_eq!(hash(u16c), hash(c));
+    assert_eq!(u16c.cmp(&u16c), Ordering::Equal);
+    assert!(u16c.eq_ignore_ascii_case(&u16c));
+
+    assert_eq!(u8c, c);
+    assert_eq!(c, u8c);
+    assert_eq!(u16c, c);
+    assert_eq!(c, u16c);
+    assert_eq!(u8c, u16c);
+    assert_eq!(u16c, u8c);
+    assert_eq!(u8c == c as u8,  c <= '\u{7F}');
+    assert_eq!(u16c == c as u8,  c <= '\u{FF}');
+    assert_eq!(u16c == c as u16,  c <= '\u{FFFF}');
+
+    assert_eq!(u8c.partial_cmp(&c), Some(Ordering::Equal));
+    assert_eq!(c.partial_cmp(&u8c), Some(Ordering::Equal));
+    assert_eq!(u16c.partial_cmp(&c), Some(Ordering::Equal));
+    assert_eq!(c.partial_cmp(&u16c), Some(Ordering::Equal));
+    assert_eq!(u8c.partial_cmp(&u16c), Some(Ordering::Equal));
+    assert_eq!(u16c.partial_cmp(&u8c), Some(Ordering::Equal));
+
+
+    for &other in &EDGES_AND_BETWEEN {
+        let u8other = other.to_utf8();
+        assert_eq!(u8c == u8other,  c == other);
+        assert_eq!(hash(u8c)==hash(u8other),  hash(c)==hash(other));
+        assert_eq!(u8c.cmp(&u8other), c.cmp(&other));
+        assert_eq!(u8c.eq_ignore_ascii_case(&u8other), c.eq_ignore_ascii_case(&other));
+        assert_eq!(u8c.partial_cmp(&other), c.partial_cmp(&other));
+        assert_eq!(c.partial_cmp(&u8other), c.partial_cmp(&other));
+        assert_eq!(u8other.partial_cmp(&c), other.partial_cmp(&c));
+        assert_eq!(other.partial_cmp(&u8c), other.partial_cmp(&c));
+        assert_eq!(u8c == other as u8,  other as u8 <= 127 && c == other as u8 as char);
+
+        let u16other = other.to_utf16();
+        assert_eq!(u16c == u16other,  c == other);
+        assert_eq!(hash(u16c)==hash(u16other),  hash(c)==hash(other));
+        assert_eq!(u16c.cmp(&u16other), c.cmp(&other));
+        assert_eq!(u16c.eq_ignore_ascii_case(&u16other), c.eq_ignore_ascii_case(&other));
+        assert_eq!(u16c.partial_cmp(&other), c.partial_cmp(&other));
+        assert_eq!(c.partial_cmp(&u16other), c.partial_cmp(&other));
+        assert_eq!(u16other.partial_cmp(&c), other.partial_cmp(&c));
+        assert_eq!(other.partial_cmp(&u16c), other.partial_cmp(&c));
+        assert_eq!(u16c == other as u8,  c == other as u8 as char);
+        assert_eq!(u16c == other as u16,  c as u32 == other as u16 as u32);
+
+        assert_eq!(u8c == u16other,  c == other);
+        assert_eq!(u16c == u8other,  c == other);
+        assert_eq!(u8c.partial_cmp(&u16other),  c.partial_cmp(&other));
+        assert_eq!(u16c.partial_cmp(&u8other),  c.partial_cmp(&other));
+        assert_eq!(u8other.partial_cmp(&u16c),  other.partial_cmp(&c));
+        assert_eq!(u16other.partial_cmp(&u8c),  other.partial_cmp(&c));
+    }
+    (u8c, u16c)
+}
+
+fn iterators(c: char) {
+    let mut iter = c.iter_utf8_bytes();
+    let mut buf = [0; 4];
+    let mut iter_ref = c.encode_utf8(&mut buf[..]).as_bytes().iter();
+    for _ in 0..6 {
+        assert_eq!(iter.size_hint(), iter_ref.size_hint());
+        assert_eq!(format!("{:?}", iter), format!("{:?}", iter_ref.as_slice()));
+        assert_eq!(iter.next(), iter_ref.next().cloned());
+    }
+
+    let mut iter = c.iter_utf16_units();
+    let mut buf = [0; 2];
+    let mut iter_ref = c.encode_utf16(&mut buf[..]).iter();
+    for _ in 0..4 {
+        assert_eq!(iter.size_hint(), iter_ref.size_hint());
+        assert_eq!(format!("{:?}", iter), format!("{:?}", iter_ref.as_slice()));
+        assert_eq!(iter.next(), iter_ref.next().cloned());
+    }
+}
+
+fn test(c: char) {
+    assert_eq!(char::from_u32(c as u32), Some(c));
+    assert_eq!(char::from_u32_detailed(c as u32), Ok(c));
+    assert_eq!(unsafe{ char::from_u32_unchecked(c as u32) }, c);
+    let (u8c, u16c) = eq_cmp_hash(c);
+    iterators(c);
+    assert_eq!(Utf16Char::from(u8c), u16c);
+    assert_eq!(Utf8Char::from(u16c), u8c);
+    let utf8_len = c.len_utf8();
+    let utf16_len = c.len_utf16();
+    let mut as_str = c.to_string();
+
+    // UTF-8
+    let mut buf = [0; 4];
+    let reference = c.encode_utf8(&mut buf[..]).as_bytes();
+    let len = reference.len(); // short name because it is used in many places.
+    assert_eq!(len, utf8_len);
+    assert_eq!(reference[0].extra_utf8_bytes(), Ok(len-1));
+    assert_eq!(reference[0].extra_utf8_bytes_unchecked(), len-1);
+    assert_eq!(AsRef::<[u8]>::as_ref(&u8c), reference);
+
+    let (arr,arrlen) = u8c.to_array();
+    assert_eq!(arrlen, len);
+    assert_eq!(Utf8Char::from_array(arr), Ok(u8c));
+    assert_eq!(c.to_utf8_array(),  (arr, len));
+
+    let str_ = str::from_utf8(reference).unwrap();
+    let ustr = Utf8Char::from_str(str_).unwrap();
+    assert_eq!(ustr.to_array().0, arr);// bitwise equality
+    assert_eq!(char::from_utf8_array(arr), Ok(c));
+    let mut longer = [0xff; 5]; // 0xff is never valid
+    longer[..len].copy_from_slice(reference);
+    assert_eq!(char::from_utf8_slice_start(reference), Ok((c,len)));
+    assert_eq!(char::from_utf8_slice_start(&longer), Ok((c,len)));
+    assert_eq!(Utf8Char::from_slice_start(reference), Ok((u8c,len)));
+    assert_eq!(Utf8Char::from_slice_start(&longer), Ok((u8c,len)));
+    for other in &mut longer[len..] {*other = b'?'}
+    assert_eq!(Utf8Char::from_str(str_), Ok(u8c));
+    assert_eq!(Utf8Char::from_str_start(str_), Ok((u8c,len)));
+    assert_eq!(Utf8Char::from_str_start(str::from_utf8(&longer).unwrap()), Ok((u8c,len)));
+    unsafe {
+        // Hopefully make bugs easier to catch by making reads into unallocated memory by filling
+        // a jemalloc bin. See table on http://jemalloc.net/jemalloc.3.html for bin sizes.
+        // I have no idea whether this works.
+        let mut boxed = Box::new([0xffu8; 16]);
+        let start = boxed.len()-len; // reach the end
+        boxed[start..].copy_from_slice(reference);
+        let slice = &boxed[start..start]; // length of slice should be ignored.
+        assert_eq!(Utf8Char::from_slice_start_unchecked(slice), (u8c,len));
+    }
+    assert_eq!(&Vec::<u8>::from_iter(Some(u8c))[..], reference);
+    assert_eq!(&String::from_iter(Some(u8c))[..], str_);
+    assert_eq!(format!("{:?}", u8c), format!("{:?}", c));
+    assert_eq!(format!("{}", u8c), format!("{}", c));
+    assert_eq!(u8c.is_ascii(), c.is_ascii());
+    assert_eq!(u8c.to_ascii_lowercase().to_char(), c.to_ascii_lowercase());
+    assert_eq!(u8c.to_ascii_uppercase().to_char(), c.to_ascii_uppercase());
+
+    // UTF-16
+    let mut buf = [0; 2];
+    let reference = c.encode_utf16(&mut buf[..]);
+    let len = reference.len();
+    assert_eq!(len, utf16_len);
+    assert_eq!(reference[0].utf16_needs_extra_unit(), Ok(len==2));
+    assert_eq!(reference[0].is_utf16_leading_surrogate(), len==2);
+    assert_eq!(u16c.as_ref(), reference);
+    let mut longer = [0; 3];
+    longer[..len].copy_from_slice(reference);
+    assert_eq!(char::from_utf16_slice_start(reference), Ok((c,len)));
+    assert_eq!(char::from_utf16_slice_start(&longer), Ok((c,len)));
+    assert_eq!(Utf16Char::from_slice_start(reference), Ok((u16c,len)));
+    assert_eq!(Utf16Char::from_slice_start(&longer), Ok((u16c,len)));
+    assert_eq!(Utf16Char::from_str(&as_str), Ok(u16c));
+    as_str.push(c);
+    assert_eq!(Utf16Char::from_str_start(&as_str), Ok((u16c,utf8_len)));
+    unsafe {
+        // Hopefully make bugs easier to catch by making reads into unallocated memory by filling
+        // a jemalloc bin. See table on http://jemalloc.net/jemalloc.3.html for bin sizes.
+        // I have no idea whether this works.
+        let mut boxed = Box::new([0u16; 8]);
+        let start = boxed.len()-len; // reach the end
+        boxed[start..].copy_from_slice(reference);
+        let slice = &boxed[start..start]; // length of slice should be ignored.
+        assert_eq!(Utf16Char::from_slice_start_unchecked(slice), (u16c,len));
+    }
+    let array = c.to_utf16_array();
+    let tuple = c.to_utf16_tuple();
+    assert_eq!(&array[..reference.len()], reference);
+    assert_eq!(tuple, (reference[0],reference.get(1).cloned()));
+    assert_eq!(char::from_utf16_array(array), Ok(c));
+    assert_eq!(char::from_utf16_tuple(tuple), Ok(c));
+    assert_eq!(c.to_utf16().to_char(), c);
+    assert_eq!(&Vec::<u16>::from_iter(Some(u16c))[..], reference);
+    assert_eq!(format!("{:?}", u16c), format!("{:?}", c));
+    assert_eq!(format!("{}", u16c), format!("{}", c));
+    assert_eq!(u16c.is_ascii(), c.is_ascii());
+    assert_eq!(u16c.to_ascii_lowercase().to_char(), c.to_ascii_lowercase());
+    assert_eq!(u16c.to_ascii_uppercase().to_char(), c.to_ascii_uppercase());
+}
+
+
+#[test]
+fn edges_middle() {
+    for &c in &EDGES_AND_BETWEEN {
+        test(c);
+    }
+}
+
+
+#[test]
+#[ignore]
+fn all() {
+    for cp in std::iter::Iterator::chain(0..0xd800, 0xe000..0x110000) {
+        let c = char::from_u32(cp).expect("not a valid char");
+        test(c);
+    }
+}