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/issue_2915.rs

@@ -0,0 +1,78 @@
+// 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.
+
+#![no_implicit_prelude]
+#![allow(dead_code, non_snake_case, non_camel_case_types, non_upper_case_globals)]
+
+include!("include.rs");
+
+// Original reproducer from #2915
+#[derive(imp::TryFromBytes)]
+#[zerocopy(crate = "zerocopy_renamed")]
+#[repr(u8)]
+enum MyEnum {
+    Type,
+    OtherWithData(u8),
+}
+
+// Tests for all other associated types which may be problematic in our codebase
+// as of this commit.
+
+#[derive(imp::FromBytes, imp::IntoBytes, imp::Unaligned, imp::Immutable, imp::KnownLayout)]
+#[zerocopy(crate = "zerocopy_renamed")]
+#[repr(C)]
+pub struct StructCollision {
+    pub Type: u8,
+    pub LAYOUT: u8,
+    pub PointerMetadata: u8,
+    pub Tag: u8,
+    pub tag: u8,
+    pub variants: u8,
+}
+
+impl StructCollision {
+    pub const Type: () = ();
+    pub const LAYOUT: () = ();
+    pub const PointerMetadata: () = ();
+}
+
+#[derive(imp::FromZeros, imp::Immutable, imp::KnownLayout)]
+#[zerocopy(crate = "zerocopy_renamed")]
+#[repr(C)]
+pub enum EnumCollision {
+    Type { x: u8 },
+    LAYOUT { x: u8 },
+    PointerMetadata { x: u8 },
+    Tag { x: u8 },
+    tag { x: u8 },
+    variants { x: u8 },
+}
+
+// Case where generic parameter has associated type colliding with internal usage
+pub trait AmbiguousTrait {
+    type Type;
+    const LAYOUT: usize;
+    type PointerMetadata;
+}
+
+#[derive(imp::FromBytes, imp::IntoBytes, imp::Unaligned, imp::Immutable, imp::KnownLayout)]
+#[zerocopy(crate = "zerocopy_renamed")]
+#[repr(C)]
+pub struct GenericCollision<T: AmbiguousTrait> {
+    pub field: u8,
+    pub typ: T::Type,
+    pub pointer_metadata: T::PointerMetadata,
+    pub _marker: imp::PhantomData<T>,
+}
+
+#[test]
+fn test_compilation() {
+    // If the derives compile, we are good.
+    let _ = StructCollision { Type: 0, LAYOUT: 0, PointerMetadata: 0, Tag: 0, tag: 0, variants: 0 };
+    let _ = EnumCollision::Type { x: 0 };
+}