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/pin-project-lite/tests/proper_unpin.rs

@@ -0,0 +1,101 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+#![allow(dead_code)]
+
+#[macro_use]
+mod auxiliary;
+
+pub mod default {
+    use std::marker::PhantomPinned;
+
+    use pin_project_lite::pin_project;
+
+    struct Inner<T> {
+        f: T,
+    }
+
+    assert_unpin!(Inner<()>);
+    assert_not_unpin!(Inner<PhantomPinned>);
+
+    pin_project! {
+        struct Struct<T, U> {
+            #[pin]
+            f1: Inner<T>,
+            f2: U,
+        }
+    }
+
+    assert_unpin!(Struct<(), ()>);
+    assert_unpin!(Struct<(), PhantomPinned>);
+    assert_not_unpin!(Struct<PhantomPinned, ()>);
+    assert_not_unpin!(Struct<PhantomPinned, PhantomPinned>);
+
+    pin_project! {
+        #[project = EnumProj]
+        #[project_ref = EnumProjRef]
+        enum Enum<T, U> {
+            V1 {
+                #[pin]
+                f1: Inner<T>,
+                f2: U,
+            },
+        }
+    }
+
+    assert_unpin!(Enum<(), ()>);
+    assert_unpin!(Enum<(), PhantomPinned>);
+    assert_not_unpin!(Enum<PhantomPinned, ()>);
+    assert_not_unpin!(Enum<PhantomPinned, PhantomPinned>);
+
+    pin_project! {
+        #[project(!Unpin)]
+        enum NotUnpinEnum<T, U> {
+            V1 {
+                #[pin] f1: Inner<T>,
+                f2: U,
+            }
+        }
+    }
+
+    assert_not_unpin!(NotUnpinEnum<(), ()>);
+
+    pin_project! {
+        struct TrivialBounds {
+            #[pin]
+            f: PhantomPinned,
+        }
+    }
+
+    assert_not_unpin!(TrivialBounds);
+
+    pin_project! {
+        struct PinRef<'a, T, U> {
+            #[pin]
+            f1: &'a mut Inner<T>,
+            f2: U,
+        }
+    }
+
+    assert_unpin!(PinRef<'_, PhantomPinned, PhantomPinned>);
+
+    pin_project! {
+        #[project(!Unpin)]
+        struct NotUnpin<U> {
+            #[pin]
+            u: U
+        }
+    }
+
+    assert_not_unpin!(NotUnpin<()>);
+
+    pin_project! {
+        #[project(!Unpin)]
+        struct NotUnpinRef<'a, T, U> {
+            #[pin]
+            f1: &'a mut Inner<T>,
+            f2: U
+        }
+    }
+
+    assert_not_unpin!(NotUnpinRef<'_, (), ()>);
+}