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/zerocopy-derive/tests/struct_try_from_bytes.rs

@@ -0,0 +1,223 @@
+// Copyright 2023 The Fuchsia Authors
+//
+// Licensed under a BSD-style license <LICENSE-BSD>, Apache License, Version 2.0
+// <LICENSE-APACHE or https://www.apache.org/licenses/LICENSE-2.0>, or the MIT
+// license <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your option.
+// This file may not be copied, modified, or distributed except according to
+// those terms.
+
+// See comment in `include.rs` for why we disable the prelude.
+#![no_implicit_prelude]
+#![allow(warnings)]
+
+include!("include.rs");
+
+// A struct is `imp::TryFromBytes` if:
+// - all fields are `imp::TryFromBytes`
+
+#[test]
+fn zst() {
+    crate::util::test_is_bit_valid::<(), _>((), true);
+}
+
+#[derive(imp::TryFromBytes, imp::Immutable, imp::IntoBytes)]
+#[zerocopy(crate = "zerocopy_renamed")]
+#[repr(C)]
+struct One {
+    a: u8,
+}
+
+util_assert_impl_all!(One: imp::TryFromBytes);
+
+#[test]
+fn one() {
+    crate::util::test_is_bit_valid::<One, _>(One { a: 42 }, true);
+    crate::util::test_is_bit_valid::<One, _>(One { a: 43 }, true);
+}
+
+#[derive(imp::TryFromBytes, imp::Immutable, imp::IntoBytes)]
+#[zerocopy(crate = "zerocopy_renamed")]
+#[repr(C)]
+struct Two {
+    a: bool,
+    b: (),
+}
+
+util_assert_impl_all!(Two: imp::TryFromBytes);
+
+#[test]
+fn two() {
+    crate::util::test_is_bit_valid::<Two, _>(Two { a: false, b: () }, true);
+    crate::util::test_is_bit_valid::<Two, _>(Two { a: true, b: () }, true);
+    crate::util::test_is_bit_valid::<Two, _>([2u8], false);
+}
+
+#[derive(imp::KnownLayout, imp::TryFromBytes)]
+#[zerocopy(crate = "zerocopy_renamed")]
+#[repr(C)]
+struct Unsized {
+    a: [u8],
+}
+
+util_assert_impl_all!(Unsized: imp::TryFromBytes);
+
+#[test]
+fn un_sized() {
+    // FIXME(#5): Use `try_transmute` in this test once it's available.
+    let mut buf = [16u8, 12, 42];
+    let candidate = ::zerocopy_renamed::Ptr::from_mut(&mut buf[..]);
+    // SAFETY: `&Unsized` consists entirely of initialized bytes.
+    let candidate = unsafe { candidate.assume_initialized() };
+
+    let mut candidate = {
+        use imp::pointer::{cast::CastUnsized, BecauseExclusive};
+        candidate.cast::<_, CastUnsized, (_, BecauseExclusive)>()
+    };
+
+    // SAFETY: `candidate`'s referent is as-initialized as `Two`.
+    let mut candidate = unsafe { candidate.assume_initialized() };
+    let is_bit_valid = <Unsized as imp::TryFromBytes>::is_bit_valid(candidate.reborrow_shared());
+    imp::assert!(is_bit_valid);
+}
+
+#[derive(imp::TryFromBytes)]
+#[zerocopy(crate = "zerocopy_renamed")]
+#[repr(C)]
+struct TypeParams<'a, T: ?imp::Sized, I: imp::Iterator> {
+    a: I::Item,
+    b: u8,
+    c: imp::PhantomData<&'a [u8]>,
+    d: imp::PhantomData<&'static str>,
+    e: imp::PhantomData<imp::String>,
+    f: T,
+}
+
+util_assert_impl_all!(TypeParams<'static, (), imp::IntoIter<()>>: imp::TryFromBytes);
+util_assert_impl_all!(TypeParams<'static, util::AU16, imp::IntoIter<()>>: imp::TryFromBytes);
+util_assert_impl_all!(TypeParams<'static, [util::AU16], imp::IntoIter<()>>: imp::TryFromBytes);
+
+// Deriving `imp::TryFromBytes` should work if the struct has bounded
+// parameters.
+
+#[derive(imp::TryFromBytes)]
+#[zerocopy(crate = "zerocopy_renamed")]
+#[repr(transparent)]
+struct WithParams<'a: 'b, 'b: 'a, T: 'a + 'b + imp::TryFromBytes, const N: usize>(
+    imp::PhantomData<&'a &'b ()>,
+    [T],
+)
+where
+    'a: 'b,
+    'b: 'a,
+    T: 'a + 'b + imp::TryFromBytes;
+
+util_assert_impl_all!(WithParams<'static, 'static, u8, 42>: imp::TryFromBytes);
+
+#[derive(imp::FromBytes, imp::IntoBytes)]
+#[zerocopy(crate = "zerocopy_renamed")]
+#[repr(C)]
+struct MaybeFromBytes<T>(T);
+
+#[test]
+fn test_maybe_from_bytes() {
+    // When deriving `FromBytes` on a type with no generic parameters, we emit a
+    // trivial `is_bit_valid` impl that always returns true. This test confirms
+    // that we *don't* spuriously do that when generic parameters are present.
+
+    crate::util::test_is_bit_valid::<MaybeFromBytes<bool>, _>(MaybeFromBytes(false), true);
+    crate::util::test_is_bit_valid::<MaybeFromBytes<bool>, _>(MaybeFromBytes(true), true);
+    crate::util::test_is_bit_valid::<MaybeFromBytes<bool>, _>([2u8], false);
+}
+
+#[derive(Debug, PartialEq, Eq, imp::TryFromBytes, imp::Immutable, imp::KnownLayout)]
+#[zerocopy(crate = "zerocopy_renamed")]
+#[repr(C, packed)]
+struct CPacked {
+    a: u8,
+    // NOTE: The `u32` type is not guaranteed to have alignment 4, although it
+    // does on many platforms. However, to fix this would require a custom type
+    // with a `#[repr(align(4))]` attribute, and `#[repr(packed)]` types are not
+    // allowed to transitively contain `#[repr(align(...))]` types. Thus, we
+    // have no choice but to use `u32` here. Luckily, these tests run in CI on
+    // platforms on which `u32` has alignment 4, so this isn't that big of a
+    // deal.
+    b: u32,
+}
+
+#[test]
+fn c_packed() {
+    let candidate = &[42u8, 0xFF, 0xFF, 0xFF, 0xFF];
+    let converted = <CPacked as imp::TryFromBytes>::try_ref_from_bytes(candidate);
+    imp::assert_eq!(converted, imp::Ok(&CPacked { a: 42, b: u32::MAX }));
+}
+
+#[derive(imp::TryFromBytes, imp::KnownLayout, imp::Immutable)]
+#[zerocopy(crate = "zerocopy_renamed")]
+#[repr(C, packed)]
+struct CPackedUnsized {
+    a: u8,
+    // NOTE: The `u32` type is not guaranteed to have alignment 4, although it
+    // does on many platforms. However, to fix this would require a custom type
+    // with a `#[repr(align(4))]` attribute, and `#[repr(packed)]` types are not
+    // allowed to transitively contain `#[repr(align(...))]` types. Thus, we
+    // have no choice but to use `u32` here. Luckily, these tests run in CI on
+    // platforms on which `u32` has alignment 4, so this isn't that big of a
+    // deal.
+    b: [u32],
+}
+
+#[test]
+fn c_packed_unsized() {
+    let candidate = &[42u8, 0xFF, 0xFF, 0xFF, 0xFF];
+    let converted = <CPackedUnsized as imp::TryFromBytes>::try_ref_from_bytes(candidate);
+    imp::assert!(converted.is_ok());
+}
+
+#[derive(imp::TryFromBytes)]
+#[zerocopy(crate = "zerocopy_renamed")]
+#[repr(packed)]
+struct PackedUnsized {
+    a: u8,
+    // NOTE: The `u32` type is not guaranteed to have alignment 4, although it
+    // does on many platforms. However, to fix this would require a custom type
+    // with a `#[repr(align(4))]` attribute, and `#[repr(packed)]` types are not
+    // allowed to transitively contain `#[repr(align(...))]` types. Thus, we
+    // have no choice but to use `u32` here. Luckily, these tests run in CI on
+    // platforms on which `u32` has alignment 4, so this isn't that big of a
+    // deal.
+    b: [u32],
+}
+
+#[test]
+fn packed_unsized() {
+    let candidate = &[42u8, 0xFF, 0xFF, 0xFF, 0xFF];
+    let converted = <CPackedUnsized as imp::TryFromBytes>::try_ref_from_bytes(candidate);
+    imp::assert!(converted.is_ok());
+
+    let candidate = &[42u8, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF];
+    let converted = <CPackedUnsized as imp::TryFromBytes>::try_ref_from_bytes(candidate);
+    imp::assert!(converted.is_err());
+
+    let candidate = &[42u8, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF];
+    let converted = <CPackedUnsized as imp::TryFromBytes>::try_ref_from_bytes(candidate);
+    imp::assert!(converted.is_ok());
+}
+
+#[derive(imp::TryFromBytes)]
+#[zerocopy(crate = "zerocopy_renamed")]
+struct A;
+
+#[derive(imp::TryFromBytes)]
+#[zerocopy(crate = "zerocopy_renamed")]
+struct B {
+    a: A,
+}
+
+#[derive(imp::TryFromBytes)]
+#[zerocopy(crate = "zerocopy_renamed")]
+#[repr(C)]
+struct RawIdent {
+    r#type: u8,
+}
+
+util_assert_impl_all!(RawIdent: imp::TryFromBytes);