refactor: unify SimpleLed via embedded-hal, remove Option<L> from BoardParts

- Added embedded-hal 1.0 as direct dep (already transitive via embedded-hal-async)
- SimpleLed<P: OutputPin> now generic over any HAL — single definition in driver/
- Removed duplicate SimpleLed from board/esp32s3.rs and board/wio_tracker_l1.rs
- Changed BoardParts.led from Option<L> to L — boards with no LED use ()
- Display task calls led.set_rgb() unconditionally (no-op for () boards)
- RAK board: led: () instead of led: None

Cargo.toml

@@ -21,6 +21,7 @@ categories = ["embedded", "hardware-support", "no-std"]
 cfg-if = "1.0"
 critical-section = "1.2"
 defmt = "1.0"
+embedded-hal = "1.0"
 embedded-hal-async = "1.0"
 embassy-embedded-hal = "0.6"
 embassy-executor = "0.9"