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/on_error.rs

@@ -0,0 +1,169 @@
+// Copyright 2026 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)]
+#![cfg_attr(__ZEROCOPY_INTERNAL_USE_ONLY_NIGHTLY_FEATURES_IN_TESTS, feature(trivial_bounds))]
+
+include!("include.rs");
+
+#[derive(imp::FromBytes)]
+#[zerocopy(on_error = "fail")]
+#[zerocopy(crate = "zerocopy_renamed")]
+struct LoudValid;
+
+util_assert_impl_all!(LoudValid: imp::FromBytes);
+
+// `derive(Unaligned)` fails without a repr.
+#[derive(imp::FromBytes, imp::IntoBytes, imp::Unaligned)]
+#[zerocopy(on_error = "skip")]
+#[zerocopy(crate = "zerocopy_renamed")]
+struct Foo {
+    a: u8,
+}
+
+util_assert_impl_all!(Foo: imp::FromBytes, imp::IntoBytes);
+util_assert_not_impl_any!(Foo: imp::Unaligned);
+
+// Invalid enum for FromZeros (must have discriminant 0).
+#[derive(imp::FromZeros)]
+#[zerocopy(on_error = "skip")]
+#[zerocopy(crate = "zerocopy_renamed")]
+#[repr(u8)]
+enum BadFromZerosEnum {
+    A = 1,
+    B = 2,
+}
+
+util_assert_not_impl_any!(BadFromZerosEnum: imp::FromZeros);
+
+// Invalid enum for FromBytes (must have 256 variants).
+#[derive(imp::FromBytes)]
+#[zerocopy(on_error = "skip")]
+#[zerocopy(crate = "zerocopy_renamed")]
+#[repr(u8)]
+enum BadFromBytesEnum {
+    A = 0,
+}
+
+util_assert_not_impl_any!(BadFromBytesEnum: imp::FromBytes);
+
+// Invalid enum for IntoBytes (invalid repr).
+#[derive(imp::IntoBytes)]
+#[zerocopy(on_error = "skip")]
+#[zerocopy(crate = "zerocopy_renamed")]
+#[cfg_attr(
+    any(
+        __ZEROCOPY_INTERNAL_USE_ONLY_TOOLCHAIN = "nightly",
+        __ZEROCOPY_INTERNAL_USE_ONLY_TOOLCHAIN = "stable"
+    ),
+    repr(Rust)
+)]
+enum BadIntoBytesEnum {
+    A,
+}
+
+util_assert_not_impl_any!(BadIntoBytesEnum: imp::IntoBytes);
+
+// Invalid enum for Unaligned (invalid repr).
+#[derive(imp::Unaligned)]
+#[zerocopy(on_error = "skip")]
+#[zerocopy(crate = "zerocopy_renamed")]
+#[repr(u16)]
+enum BadUnalignedEnum {
+    A,
+}
+
+util_assert_not_impl_any!(BadUnalignedEnum: imp::Unaligned);
+
+// Invalid enum for TryFromBytes (invalid repr).
+#[derive(imp::TryFromBytes)]
+#[zerocopy(on_error = "skip")]
+#[zerocopy(crate = "zerocopy_renamed")]
+#[cfg_attr(
+    any(
+        __ZEROCOPY_INTERNAL_USE_ONLY_TOOLCHAIN = "nightly",
+        __ZEROCOPY_INTERNAL_USE_ONLY_TOOLCHAIN = "stable"
+    ),
+    repr(Rust)
+)]
+enum BadTryFromBytesEnum {
+    A,
+}
+
+util_assert_not_impl_any!(BadTryFromBytesEnum: imp::TryFromBytes);
+
+// Invalid union for IntoBytes (invalid repr).
+#[derive(imp::IntoBytes)]
+#[zerocopy(on_error = "skip")]
+#[zerocopy(crate = "zerocopy_renamed")]
+#[cfg_attr(
+    any(
+        __ZEROCOPY_INTERNAL_USE_ONLY_TOOLCHAIN = "nightly",
+        __ZEROCOPY_INTERNAL_USE_ONLY_TOOLCHAIN = "stable"
+    ),
+    repr(Rust)
+)]
+union BadIntoBytesUnion {
+    a: u8,
+}
+
+util_assert_not_impl_any!(BadIntoBytesUnion: imp::IntoBytes);
+
+// Invalid union for Unaligned (invalid repr).
+#[derive(imp::Unaligned)]
+#[zerocopy(on_error = "skip")]
+#[zerocopy(crate = "zerocopy_renamed")]
+#[cfg_attr(
+    any(
+        __ZEROCOPY_INTERNAL_USE_ONLY_TOOLCHAIN = "nightly",
+        __ZEROCOPY_INTERNAL_USE_ONLY_TOOLCHAIN = "stable"
+    ),
+    repr(Rust)
+)]
+union BadUnalignedUnion {
+    a: u8,
+}
+
+util_assert_not_impl_any!(BadUnalignedUnion: imp::Unaligned);
+
+// Invalid union for IntoBytes (generic).
+#[derive(imp::IntoBytes)]
+#[zerocopy(on_error = "skip")]
+#[zerocopy(crate = "zerocopy_renamed")]
+#[repr(C)]
+union BadIntoBytesUnionGeneric<T: imp::Copy> {
+    a: T,
+}
+
+util_assert_not_impl_any!(BadIntoBytesUnionGeneric<u8>: imp::IntoBytes);
+
+#[cfg(__ZEROCOPY_INTERNAL_USE_ONLY_NIGHTLY_FEATURES_IN_TESTS)]
+mod trivial_bounds {
+    use super::*;
+
+    #[derive(imp::FromBytes)]
+    #[zerocopy(on_error = "skip")]
+    #[zerocopy(crate = "zerocopy_renamed")]
+    #[repr(transparent)]
+    struct TrivialBounds(bool);
+
+    util_assert_not_impl_any!(TrivialBounds: imp::FromBytes);
+
+    #[derive(imp::IntoBytes)]
+    #[zerocopy(on_error = "skip")]
+    #[zerocopy(crate = "zerocopy_renamed")]
+    #[repr(C)]
+    struct BadIntoBytesStructPadding {
+        a: u8,
+        b: u16,
+    }
+
+    util_assert_not_impl_any!(BadIntoBytesStructPadding: imp::IntoBytes);
+}