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/maybe-async-cfg/tests/ui/01-maybe-async.rs

@@ -0,0 +1,64 @@
+#![allow(dead_code)]
+
+#[maybe_async_cfg::maybe(send="Send", sync(feature = "is_sync"), async(not(feature = "is_sync"), async_trait::async_trait))]
+trait Trait {
+    fn sync_fn() {}
+
+    async fn declare_async(&self);
+
+    async fn async_fn(&self) {
+        self.declare_async().await
+    }
+}
+
+#[maybe_async_cfg::maybe(send="?Send", sync(feature = "is_sync"), async(not(feature = "is_sync"), async_trait::async_trait))]
+pub trait PubTrait {
+    fn sync_fn() {}
+
+    async fn declare_async(&self);
+
+    async fn async_fn(&self) {
+        self.declare_async().await
+    }
+}
+
+#[maybe_async_cfg::maybe(keep_self, sync(feature = "is_sync"), async(not(feature = "is_sync")))]
+async fn async_fn() {}
+
+#[maybe_async_cfg::maybe(keep_self, sync(feature = "is_sync"), async(not(feature = "is_sync")))]
+pub async fn pub_async_fn() {
+}
+
+struct Struct;
+
+#[maybe_async_cfg::maybe(keep_self, idents(Trait), sync(feature = "is_sync"), async(not(feature = "is_sync"), async_trait::async_trait))]
+impl Trait for Struct {
+    fn sync_fn() {}
+
+    async fn declare_async(&self) {}
+
+    async fn async_fn(&self) {
+        async { self.declare_async().await }.await
+    }
+}
+
+#[cfg(feature = "is_sync")]
+fn main() -> std::result::Result<(), ()> {
+    let s = Struct;
+    s.declare_async();
+    s.async_fn();
+    async_fn();
+    pub_async_fn();
+    Ok(())
+}
+
+
+#[cfg(not(feature = "is_sync"))]
+#[async_std::main]
+async fn main() {
+    let s = Struct;
+    s.declare_async().await;
+    s.async_fn().await;
+    async_fn().await;
+    pub_async_fn().await;
+}

vendor/maybe-async-cfg/tests/ui/02-must-be-async.rs

@@ -0,0 +1,76 @@
+#![allow(dead_code)]
+
+#[maybe_async_cfg::maybe(send="Send", async(not(feature = "is_sync"), async_trait::async_trait))]
+trait Trait {
+    fn sync_fn() {}
+
+    async fn declare_async(&self);
+
+    async fn async_fn(&self) {
+        self.declare_async().await
+    }
+}
+
+#[maybe_async_cfg::maybe(send="?Send", async(not(feature = "is_sync"), async_trait::async_trait))]
+trait NotSendTrait {
+    async fn declare_async_not_send(&self);
+
+    async fn async_fn_not_send(&self) {
+        self.declare_async_not_send().await
+    }
+}
+#[maybe_async_cfg::maybe(send="Send", async(not(feature = "is_sync"), async_trait::async_trait))]
+pub trait PubTrait {
+    fn sync_fn() {}
+
+    async fn declare_async(&self);
+
+    async fn async_fn(&self) {
+        self.declare_async().await
+    }
+}
+
+
+#[maybe_async_cfg::maybe(keep_self, async(not(feature = "is_sync")))]
+async fn async_fn() {}
+
+
+#[maybe_async_cfg::maybe(keep_self, async(not(feature = "is_sync")))]
+pub async fn pub_async_fn() {}
+
+struct Struct;
+
+
+#[maybe_async_cfg::maybe(keep_self, idents(Trait), async(not(feature = "is_sync"), async_trait::async_trait))]
+impl Trait for Struct {
+    fn sync_fn() {}
+
+    async fn declare_async(&self) {}
+
+    async fn async_fn(&self) {
+        async { self.declare_async().await }.await
+    }
+}
+
+#[maybe_async_cfg::maybe(keep_self, idents(NotSendTrait), send="?Send", async(not(feature = "is_sync"), async_trait::async_trait))]
+impl NotSendTrait for Struct {
+    async fn declare_async_not_send(&self) {}
+
+    async fn async_fn_not_send(&self) {
+        async { self.declare_async_not_send().await }.await
+    }
+}
+
+#[cfg(feature = "is_sync")]
+fn main() {}
+
+
+#[cfg(not(feature = "is_sync"))]
+#[async_std::main]
+async fn main() {
+    let s = Struct;
+    s.declare_async().await;
+    s.async_fn().await;
+    async_fn().await;
+    pub_async_fn().await;
+}

vendor/maybe-async-cfg/tests/ui/03-must-be-sync.rs

@@ -0,0 +1,57 @@
+#![allow(dead_code)]
+
+#[maybe_async_cfg::maybe(sync(feature = "is_sync"))]
+trait Trait {
+    fn sync_fn() {}
+
+    async fn declare_async(&self);
+
+    async fn async_fn(&self) {
+        self.declare_async().await
+    }
+}
+
+#[maybe_async_cfg::maybe(sync(feature = "is_sync"))]
+pub trait PubTrait {
+    fn sync_fn() {}
+
+    async fn declare_async(&self);
+
+    async fn async_fn(&self) {
+        self.declare_async().await
+    }
+}
+
+#[maybe_async_cfg::maybe(keep_self, sync(feature = "is_sync"))]
+async fn async_fn() {}
+
+#[maybe_async_cfg::maybe(keep_self, sync(feature = "is_sync"))]
+pub async fn pub_async_fn() {}
+
+struct Struct;
+
+#[maybe_async_cfg::maybe(keep_self, idents(Trait), sync(feature = "is_sync"))]
+impl Trait for Struct {
+    fn sync_fn() {}
+
+    async fn declare_async(&self) {}
+
+    async fn async_fn(&self) {
+        async { self.declare_async().await }.await
+    }
+}
+
+#[cfg(feature = "is_sync")]
+fn main() -> std::result::Result<(), ()> {
+    let s = Struct;
+    s.declare_async();
+    s.async_fn();
+    async_fn();
+    pub_async_fn();
+    Ok(())
+}
+
+
+#[cfg(not(feature = "is_sync"))]
+#[async_std::main]
+async fn main() {}

vendor/maybe-async-cfg/tests/ui/04-unit-test-util.rs

@@ -0,0 +1,37 @@
+#[maybe_async_cfg::maybe(sync(feature = "is_sync"), async(not(feature = "is_sync")))]
+async fn async_fn() -> bool {
+    true
+}
+
+#[maybe_async_cfg::maybe(
+    idents(async_fn),
+    sync(feature = "is_sync", test),
+    async(all(not(feature="is_sync"), feature = "async_std"), async_std::test),
+    async(all(not(feature="is_sync"), feature = "tokio"), tokio::test)
+)]
+async fn test_async_fn() {
+    let res = async_fn().await;
+    assert_eq!(res, true);
+}
+
+#[maybe_async_cfg::maybe(sync(feature = "is_sync", test), async(not(feature = "is_sync"), async_std::test))]
+async fn test_async_fn2() {
+    let res = async_fn().await;
+    assert_eq!(res, true);
+}
+
+#[maybe_async_cfg::maybe(sync(feature = "is_sync", test), async(not(feature = "is_sync"), async_std::test))]
+async fn test_async_fn3() {
+    let res = async_fn().await;
+    assert_eq!(res, true);
+}
+
+#[maybe_async_cfg::maybe(sync(feature = "is_sync", test), async(not(feature = "is_sync"), async_std::test))]
+async fn test_async_fn4() {
+    let res = async_fn().await;
+    assert_eq!(res, true);
+}
+
+fn main() {
+
+}

vendor/maybe-async-cfg/tests/ui/05-replace-future-generic-type-with-output.rs

@@ -0,0 +1,34 @@
+#![allow(unused_imports)]
+use std::future::Future;
+
+#[maybe_async_cfg::maybe(keep_self, sync(feature = "is_sync"), async(not(feature = "is_sync")))]
+pub async fn with_fn<T, F: Sync + std::future::Future<Output = Result<(), ()>>>(
+    test: T,
+) -> Result<(), ()>
+    where
+        T: FnOnce() -> F,
+{
+    test().await
+}
+
+#[maybe_async_cfg::maybe(keep_self, sync(feature = "is_sync"), async(not(feature = "is_sync")))]
+pub async fn with_fn_where<T, F>(test: T) -> Result<(), ()>
+    where
+        T: FnOnce() -> F,
+        F: Sync + Future<Output = Result<(), ()>>,
+{
+    test().await
+}
+
+#[maybe_async_cfg::maybe(keep_self, sync(feature = "is_sync"))]
+fn main() {
+    with_fn(|| Ok(())).unwrap();
+    with_fn_where(|| Ok(())).unwrap();
+}
+
+#[maybe_async_cfg::maybe(keep_self, async(not(feature = "is_sync")))]
+#[tokio::main]
+async fn main() {
+    with_fn(|| async { Ok(()) }).await.unwrap();
+    with_fn_where(|| async { Ok(()) }).await.unwrap();
+}

vendor/maybe-async-cfg/tests/ui/06-sync_impl_async_impl.rs

@@ -0,0 +1,48 @@
+#![allow(dead_code, unused_variables)]
+
+/// InnerClient differ a lot between sync and async.
+#[maybe_async_cfg::maybe(sync(feature = "is_sync"), async(not(feature = "is_sync"), async_trait::async_trait))]
+trait Trait {
+    async fn maybe_async_fn();
+}
+
+/// The higher level API for end user.
+pub struct Struct;
+
+/// Synchronous  implementation, only compiles when `is_sync` feature is off.
+/// Else the compiler will complain that *request is defined multiple times* and
+/// blabla.
+#[maybe_async_cfg::maybe(keep_self, idents(Trait), sync(feature = "is_sync"), async(not(feature = "is_sync")))]
+#[maybe_async::only_if(key="sync")]
+impl Trait for Struct {
+    fn maybe_async_fn() { }
+}
+
+/// Asynchronous implementation, only compiles when `is_sync` feature is off.
+#[maybe_async_cfg::maybe(keep_self, idents(Trait), sync(feature = "is_sync"), async(not(feature = "is_sync"), async_trait::async_trait))]
+#[maybe_async::only_if(key="async")]
+impl Trait for Struct {
+    async fn maybe_async_fn() { }
+}
+
+#[maybe_async_cfg::maybe(keep_self, idents(Trait, another_maybe_async_fn(fn)), sync(feature = "is_sync"), async(not(feature = "is_sync")))]
+impl Struct {
+    async fn another_maybe_async_fn()  {
+        <Self as Trait>::maybe_async_fn().await
+        // When `is_sync` is toggle on, this block will compiles to:
+        // Self::maybe_async_fn()
+    }
+}
+
+#[maybe_async_cfg::maybe(keep_self, idents(another_maybe_async_fn(fn)), sync(feature = "is_sync"), async(not(feature = "is_sync")))]
+#[maybe_async::only_if(key="sync")]
+fn main() {
+    let _ = Struct::another_maybe_async_fn();
+}
+
+#[maybe_async_cfg::maybe(keep_self, idents(another_maybe_async_fn(fn)), sync(feature = "is_sync"), async(not(feature = "is_sync")))]
+#[maybe_async::only_if(key="async")]
+#[tokio::main]
+async fn main() {
+    let _ = Struct::another_maybe_async_fn().await;
+}

vendor/maybe-async-cfg/tests/ui/test_fail/01-empty-test.rs

@@ -0,0 +1,20 @@
+#[maybe_async_cfg::maybe(
+    sync(feature = "is_sync"), 
+)]
+async fn async_fn() -> bool {
+    true
+}
+
+#[maybe_async_cfg::maybe(
+    idents(async_fn(fn)),
+    sync(feature = "is_sync"), 
+    async(not(feature = "is_sync")),
+)]
+async fn test_async_fn() {
+    let res = async_fn().await;
+    assert_eq!(res, true);
+}
+
+fn main() {
+
+}

vendor/maybe-async-cfg/tests/ui/test_fail/01-empty-test.stderr

@@ -0,0 +1,5 @@
+error[E0425]: cannot find function `async_fn_async` in this scope
+  --> tests/ui/test_fail/01-empty-test.rs:14:15
+   |
+14 |     let res = async_fn().await;
+   |               ^^^^^^^^ not found in this scope

vendor/maybe-async-cfg/tests/ui/test_fail/02-unknown-path.rs

@@ -0,0 +1,21 @@
+#[maybe_async_cfg::maybe(
+    sync(feature = "is_sync"), 
+    unknown(not(feature = "is_sync")),
+)]
+async fn async_fn() -> bool {
+    true
+}
+
+#[maybe_async_cfg::maybe(
+    idents(async_fn(fn)),
+    sync(feature = "is_sync"), 
+    async(not(feature = "is_sync")),
+)]
+async fn test_async_fn() {
+    let res = async_fn().await;
+    assert_eq!(res, true);
+}
+
+fn main() {
+
+}

vendor/maybe-async-cfg/tests/ui/test_fail/02-unknown-path.stderr

@@ -0,0 +1,5 @@
+error[E0425]: cannot find function `async_fn_async` in this scope
+  --> tests/ui/test_fail/02-unknown-path.rs:15:15
+   |
+15 |     let res = async_fn().await;
+   |               ^^^^^^^^ not found in this scope

vendor/maybe-async-cfg/tests/ui/test_fail/03-async-gt2.rs

@@ -0,0 +1,23 @@
+#[maybe_async_cfg::maybe(
+    sync(feature = "is_sync"), 
+    async(not(feature = "is_sync")),
+)]
+async fn async_fn() -> bool {
+    true
+}
+
+//#[maybe_async::test(feature="is_sync", async(feature="async", async_std::test, added))]
+#[maybe_async_cfg::maybe(
+    idents(async_fn(fn)),
+    sync(feature = "is_sync"), 
+    async(not(feature = "is_sync")),
+    async(not(feature = "is_sync")),
+)]
+async fn test_async_fn() {
+    let res = async_fn().await;
+    assert_eq!(res, true);
+}
+
+fn main() {
+
+}

vendor/maybe-async-cfg/tests/ui/test_fail/03-async-gt2.stderr

@@ -0,0 +1,10 @@
+error[E0428]: the name `test_async_fn_async` is defined multiple times
+  --> tests/ui/test_fail/03-async-gt2.rs:16:1
+   |
+16 | async fn test_async_fn() {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^
+   | |
+   | `test_async_fn_async` redefined here
+   | previous definition of the value `test_async_fn_async` here
+   |
+   = note: `test_async_fn_async` must be defined only once in the value namespace of this module

vendor/maybe-async-cfg/tests/ui/test_fail/04-bad-sync-cond.rs

@@ -0,0 +1,23 @@
+#[maybe_async_cfg::maybe(
+    sync(feature = "is_sync"), 
+    async(not(feature = "is_sync")),
+)]
+async fn async_fn() -> bool {
+    true
+}
+
+// bad sync condition
+//#[maybe_async::test(unknown(feature="async", async_std::test))]
+#[maybe_async_cfg::maybe(
+    idents(async_fn(fn)),
+    sync(unknown = "is_sync"), 
+    async(not(feature = "is_sync")),
+)]
+async fn test_async_fn() {
+    let res = async_fn().await;
+    assert_eq!(res, true);
+}
+
+fn main() {
+
+}

vendor/maybe-async-cfg/tests/ui/test_fail/04-bad-sync-cond.stderr

@@ -0,0 +1,5 @@
+error: Wrong name for name-value pair: unknown
+  --> tests/ui/test_fail/04-bad-sync-cond.rs:13:10
+   |
+13 |     sync(unknown = "is_sync"),
+   |          ^^^^^^^^^^^^^^^^^^^