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/ui/privacy.rs

@@ -0,0 +1,160 @@
+// Copyright 2025 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.
+
+#![allow(unused_braces)]
+
+#[macro_use]
+extern crate zerocopy_renamed;
+
+fn main() {}
+
+// These tests cause errors which are generated by a later compilation pass than
+// the other errors we generate, and so if they're compiled in the same file,
+// the compiler will never get to that pass, and so we won't get the errors.
+
+mod private {
+    #[derive(TryFromBytes)]
+    #[zerocopy(crate = "zerocopy_renamed")]
+    pub struct StructWithNamedFields {
+        pub a: u8,
+        pub(self) b: u16,
+    }
+
+    const _: () = {
+        let _: <StructWithNamedFields as zerocopy_renamed::HasField<
+            _,
+            _,
+            //~[msrv]^ ERROR: type provided when a constant was expected
+            { zerocopy_renamed::ident_id!(a) },
+        >>::Type = 0u8;
+        let _: <StructWithNamedFields as zerocopy_renamed::HasField<
+            _,
+            _,
+            //~[msrv]^ ERROR: type provided when a constant was expected
+            { zerocopy_renamed::ident_id!(b) },
+        >>::Type = 0u16;
+    };
+
+    #[derive(TryFromBytes)]
+    #[zerocopy(crate = "zerocopy_renamed")]
+    pub struct StructWithAnonFields(pub u8, pub(self) u16);
+
+    const _: () = {
+        let _: <StructWithAnonFields as zerocopy_renamed::HasField<
+            _,
+            _,
+            //~[msrv]^ ERROR: type provided when a constant was expected
+            { zerocopy_renamed::ident_id!(0) },
+        >>::Type = 0u8;
+        let _: <StructWithAnonFields as zerocopy_renamed::HasField<
+            _,
+            _,
+            //~[msrv]^ ERROR: type provided when a constant was expected
+            { zerocopy_renamed::ident_id!(1) },
+        >>::Type = 0u16;
+    };
+
+    #[derive(TryFromBytes)]
+    #[zerocopy(crate = "zerocopy_renamed")]
+    pub struct Union {
+        pub a: u8,
+        pub(self) b: u16,
+    }
+
+    const _: () = {
+        let _: <Union as zerocopy_renamed::HasField<_, _, { zerocopy_renamed::ident_id!(a) }>>::Type = 0u8;
+        //~[msrv]^ ERROR: type provided when a constant was expected
+        let _: <Union as zerocopy_renamed::HasField<_, _, { zerocopy_renamed::ident_id!(b) }>>::Type = 0u16;
+        //~[msrv]^ ERROR: type provided when a constant was expected
+    };
+
+    #[derive(TryFromBytes)]
+    #[zerocopy(crate = "zerocopy_renamed")]
+    #[repr(C)]
+    pub enum Enum {
+        A(u8, u16),
+        B { a: u8, b: u16 },
+    }
+
+    const _: () = {
+        let _: <Enum as zerocopy_renamed::HasField<_, _, { zerocopy_renamed::ident_id!(0) }>>::Type = 0u8;
+        //~[msrv]^ ERROR: type provided when a constant was expected
+        let _: <Enum as zerocopy_renamed::HasField<_, _, { zerocopy_renamed::ident_id!(1) }>>::Type = 0u16;
+        //~[msrv]^ ERROR: type provided when a constant was expected
+
+        let _: <Enum as zerocopy_renamed::HasField<_, _, { zerocopy_renamed::ident_id!(a) }>>::Type = 0u8;
+        //~[msrv]^ ERROR: type provided when a constant was expected
+        let _: <Enum as zerocopy_renamed::HasField<
+            _,
+            { zerocopy_renamed::ident_id!(B) },
+            { zerocopy_renamed::ident_id!(b) },
+        >>::Type = 0u16;
+    };
+}
+
+use private::*;
+
+const _: () = {
+    let _: <StructWithNamedFields as zerocopy_renamed::HasField<
+        _,
+        _,
+        //~[msrv]^ ERROR: type provided when a constant was expected
+        { zerocopy_renamed::ident_id!(a) },
+    >>::Type = 0u8;
+    let _: <StructWithNamedFields as zerocopy_renamed::HasField<
+        _,
+        //~[stable, nightly]^ ERROR: type `private::_::_::_::ẕb` is private
+        _,
+        //~[msrv]^ ERROR: type provided when a constant was expected
+        { zerocopy_renamed::ident_id!(b) },
+    >>::Type = 0u16;
+};
+
+const _: () = {
+    let _: <StructWithAnonFields as zerocopy_renamed::HasField<
+        _,
+        _,
+        //~[msrv]^ ERROR: type provided when a constant was expected
+        { zerocopy_renamed::ident_id!(0) },
+    >>::Type = 0u8;
+    let _: <StructWithAnonFields as zerocopy_renamed::HasField<
+        _,
+        //~[stable, nightly]^ ERROR: type `private::_::_::_::ẕ1` is private
+        _,
+        //~[msrv]^ ERROR: type provided when a constant was expected
+        { zerocopy_renamed::ident_id!(1) },
+    >>::Type = 0u16;
+};
+
+const _: () = {
+    let _: <Union as zerocopy_renamed::HasField<_, _, { zerocopy_renamed::ident_id!(a) }>>::Type =
+//~[msrv]^ ERROR: type provided when a constant was expected
+        0u8;
+    let _: <Union as zerocopy_renamed::HasField<_, _, { zerocopy_renamed::ident_id!(b) }>>::Type =
+//~[msrv]^ ERROR: type provided when a constant was expected
+//~[stable, nightly]^^ ERROR: type `private::_::_::_::ẕb` is private
+        0u16;
+};
+
+const _: () = {
+    let _: <Enum as zerocopy_renamed::HasField<_, _, { zerocopy_renamed::ident_id!(0) }>>::Type =
+//~[msrv]^ ERROR: type provided when a constant was expected
+        0u8;
+    let _: <Enum as zerocopy_renamed::HasField<_, _, { zerocopy_renamed::ident_id!(1) }>>::Type =
+//~[msrv]^ ERROR: type provided when a constant was expected
+        0u16;
+
+    let _: <Enum as zerocopy_renamed::HasField<_, _, { zerocopy_renamed::ident_id!(a) }>>::Type =
+//~[msrv]^ ERROR: type provided when a constant was expected
+        0u8;
+    let _: <Enum as zerocopy_renamed::HasField<
+        _,
+        { zerocopy_renamed::ident_id!(B) },
+        { zerocopy_renamed::ident_id!(b) },
+    >>::Type = 0u16;
+};