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/bitflags/src/tests/iter.rs

@@ -0,0 +1,299 @@
+use super::*;
+
+use crate::Flags;
+
+#[test]
+#[cfg(not(miri))] // Very slow in miri
+fn roundtrip() {
+    for a in 0u8..=255 {
+        for b in 0u8..=255 {
+            let f = TestFlags::from_bits_retain(a | b);
+
+            assert_eq!(f, f.iter().collect::<TestFlags>());
+            assert_eq!(
+                TestFlags::from_bits_truncate(f.bits()),
+                f.iter_names().map(|(_, f)| f).collect::<TestFlags>()
+            );
+
+            let f = TestExternal::from_bits_retain(a | b);
+
+            assert_eq!(f, f.iter().collect::<TestExternal>());
+        }
+    }
+}
+
+mod collect {
+    use super::*;
+
+    #[test]
+    fn cases() {
+        assert_eq!(0, [].into_iter().collect::<TestFlags>().bits());
+
+        assert_eq!(1, [TestFlags::A,].into_iter().collect::<TestFlags>().bits());
+
+        assert_eq!(
+            1 | 1 << 1 | 1 << 2,
+            [TestFlags::A, TestFlags::B | TestFlags::C,]
+                .into_iter()
+                .collect::<TestFlags>()
+                .bits()
+        );
+
+        assert_eq!(
+            1 | 1 << 3,
+            [
+                TestFlags::from_bits_retain(1 << 3),
+                TestFlags::empty(),
+                TestFlags::A,
+            ]
+            .into_iter()
+            .collect::<TestFlags>()
+            .bits()
+        );
+
+        assert_eq!(
+            1 << 5 | 1 << 7,
+            [
+                TestExternal::empty(),
+                TestExternal::from_bits_retain(1 << 5),
+                TestExternal::from_bits_retain(1 << 7),
+            ]
+            .into_iter()
+            .collect::<TestExternal>()
+            .bits()
+        );
+    }
+}
+
+mod iter {
+    use super::*;
+
+    #[test]
+    fn cases() {
+        case(&[], TestFlags::empty(), TestFlags::iter);
+
+        case(&[1], TestFlags::A, TestFlags::iter);
+        case(&[1, 1 << 1], TestFlags::A | TestFlags::B, TestFlags::iter);
+        case(
+            &[1, 1 << 1, 1 << 3],
+            TestFlags::A | TestFlags::B | TestFlags::from_bits_retain(1 << 3),
+            TestFlags::iter,
+        );
+
+        case(&[1, 1 << 1, 1 << 2], TestFlags::ABC, TestFlags::iter);
+        case(
+            &[1, 1 << 1, 1 << 2, 1 << 3],
+            TestFlags::ABC | TestFlags::from_bits_retain(1 << 3),
+            TestFlags::iter,
+        );
+
+        case(
+            &[1 | 1 << 1 | 1 << 2],
+            TestFlagsInvert::ABC,
+            TestFlagsInvert::iter,
+        );
+
+        case(&[], TestZero::ZERO, TestZero::iter);
+
+        case(
+            &[1, 1 << 1, 1 << 2, 0b1111_1000],
+            TestExternal::all(),
+            TestExternal::iter,
+        );
+    }
+
+    #[track_caller]
+    fn case<T: Flags + std::fmt::Debug + IntoIterator<Item = T> + Copy>(
+        expected: &[T::Bits],
+        value: T,
+        inherent: impl FnOnce(&T) -> crate::iter::Iter<T>,
+    ) where
+        T::Bits: std::fmt::Debug + PartialEq,
+    {
+        assert_eq!(
+            expected,
+            inherent(&value).map(|f| f.bits()).collect::<Vec<_>>(),
+            "{:?}.iter()",
+            value
+        );
+        assert_eq!(
+            expected,
+            Flags::iter(&value).map(|f| f.bits()).collect::<Vec<_>>(),
+            "Flags::iter({:?})",
+            value
+        );
+        assert_eq!(
+            expected,
+            value.into_iter().map(|f| f.bits()).collect::<Vec<_>>(),
+            "{:?}.into_iter()",
+            value
+        );
+    }
+}
+
+mod iter_names {
+    use super::*;
+
+    #[test]
+    fn cases() {
+        case(&[], TestFlags::empty(), TestFlags::iter_names);
+
+        case(&[("A", 1)], TestFlags::A, TestFlags::iter_names);
+        case(
+            &[("A", 1), ("B", 1 << 1)],
+            TestFlags::A | TestFlags::B,
+            TestFlags::iter_names,
+        );
+        case(
+            &[("A", 1), ("B", 1 << 1)],
+            TestFlags::A | TestFlags::B | TestFlags::from_bits_retain(1 << 3),
+            TestFlags::iter_names,
+        );
+
+        case(
+            &[("A", 1), ("B", 1 << 1), ("C", 1 << 2)],
+            TestFlags::ABC,
+            TestFlags::iter_names,
+        );
+        case(
+            &[("A", 1), ("B", 1 << 1), ("C", 1 << 2)],
+            TestFlags::ABC | TestFlags::from_bits_retain(1 << 3),
+            TestFlags::iter_names,
+        );
+
+        case(
+            &[("ABC", 1 | 1 << 1 | 1 << 2)],
+            TestFlagsInvert::ABC,
+            TestFlagsInvert::iter_names,
+        );
+
+        case(&[], TestZero::ZERO, TestZero::iter_names);
+
+        case(
+            &[("A", 1)],
+            TestOverlappingFull::A,
+            TestOverlappingFull::iter_names,
+        );
+        case(
+            &[("A", 1), ("D", 1 << 1)],
+            TestOverlappingFull::A | TestOverlappingFull::D,
+            TestOverlappingFull::iter_names,
+        );
+    }
+
+    #[track_caller]
+    fn case<T: Flags + std::fmt::Debug>(
+        expected: &[(&'static str, T::Bits)],
+        value: T,
+        inherent: impl FnOnce(&T) -> crate::iter::IterNames<T>,
+    ) where
+        T::Bits: std::fmt::Debug + PartialEq,
+    {
+        assert_eq!(
+            expected,
+            inherent(&value)
+                .map(|(n, f)| (n, f.bits()))
+                .collect::<Vec<_>>(),
+            "{:?}.iter_names()",
+            value
+        );
+        assert_eq!(
+            expected,
+            Flags::iter_names(&value)
+                .map(|(n, f)| (n, f.bits()))
+                .collect::<Vec<_>>(),
+            "Flags::iter_names({:?})",
+            value
+        );
+    }
+}
+
+mod iter_defined_names {
+    use crate::Flags;
+
+    #[test]
+    fn test_defined_names() {
+        bitflags! {
+            #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+            struct TestFlags: u32 {
+                const A = 0b00000001;
+                const ZERO = 0;
+                const B = 0b00000010;
+                const C = 0b00000100;
+                const CC = Self::C.bits();
+                const D = 0b10000100;
+                const ABC = Self::A.bits() | Self::B.bits() | Self::C.bits();
+                const AB = Self::A.bits() | Self::B.bits();
+                const AC = Self::A.bits() | Self::C.bits();
+                const CB = Self::B.bits() | Self::C.bits();
+            }
+        }
+
+        // Test all named flags produced by the iterator
+        let all_named: Vec<(&'static str, TestFlags)> = TestFlags::iter_defined_names().collect();
+
+        // Verify all named flags are included
+        let expected_flags = vec![
+            ("A", TestFlags::A),
+            ("ZERO", TestFlags::ZERO),
+            ("B", TestFlags::B),
+            ("C", TestFlags::C),
+            // Note: CC and C have the same bit value, but both are named flags
+            ("CC", TestFlags::CC),
+            ("D", TestFlags::D),
+            ("ABC", TestFlags::ABC),
+            ("AB", TestFlags::AB),
+            ("AC", TestFlags::AC),
+            ("CB", TestFlags::CB),
+        ];
+
+        assert_eq!(
+            all_named.len(),
+            expected_flags.len(),
+            "Should have 10 named flags"
+        );
+
+        // Verify each expected flag is in the result
+        for expected_flag in &expected_flags {
+            assert!(
+                all_named.contains(expected_flag),
+                "Missing flag: {:?}",
+                expected_flag
+            );
+        }
+
+        // Test if iterator order is consistent with definition order
+        let flags_in_order: Vec<(&'static str, TestFlags)> =
+            TestFlags::iter_defined_names().collect();
+        assert_eq!(
+            flags_in_order, expected_flags,
+            "Flag order should match definition order"
+        );
+
+        // Test that iterator can be used multiple times
+        let first_iteration: Vec<(&'static str, TestFlags)> =
+            TestFlags::iter_defined_names().collect();
+        let second_iteration: Vec<(&'static str, TestFlags)> =
+            TestFlags::iter_defined_names().collect();
+        assert_eq!(
+            first_iteration, second_iteration,
+            "Multiple iterations should produce the same result"
+        );
+
+        // Test consistency with FLAGS constant
+        let flags_from_iter: std::collections::HashSet<u32> = TestFlags::iter_defined_names()
+            .map(|(_, f)| f.bits())
+            .collect();
+
+        let flags_from_const: std::collections::HashSet<u32> = TestFlags::FLAGS
+            .iter()
+            .filter(|f| f.is_named())
+            .map(|f| f.value().bits())
+            .collect();
+
+        assert_eq!(
+            flags_from_iter, flags_from_const,
+            "iter_defined_names() should be consistent with named flags in FLAGS"
+        );
+    }
+}