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/embassy-embedded-hal/src/adapter/blocking_async.rs

@@ -0,0 +1,149 @@
+use embedded_hal_02::blocking;
+
+/// Wrapper that implements async traits using blocking implementations.
+///
+/// This allows driver writers to depend on the async traits while still supporting embedded-hal peripheral implementations.
+///
+/// BlockingAsync will implement any async trait that maps to embedded-hal traits implemented for the wrapped driver.
+///
+/// Driver users are then free to choose which implementation that is available to them.
+pub struct BlockingAsync<T> {
+    wrapped: T,
+}
+
+impl<T> BlockingAsync<T> {
+    /// Create a new instance of a wrapper for a given peripheral.
+    pub fn new(wrapped: T) -> Self {
+        Self { wrapped }
+    }
+}
+
+//
+// I2C implementations
+//
+impl<T, E> embedded_hal_1::i2c::ErrorType for BlockingAsync<T>
+where
+    E: embedded_hal_1::i2c::Error + 'static,
+    T: blocking::i2c::WriteRead<Error = E> + blocking::i2c::Read<Error = E> + blocking::i2c::Write<Error = E>,
+{
+    type Error = E;
+}
+
+impl<T, E> embedded_hal_async::i2c::I2c for BlockingAsync<T>
+where
+    E: embedded_hal_1::i2c::Error + 'static,
+    T: blocking::i2c::WriteRead<Error = E> + blocking::i2c::Read<Error = E> + blocking::i2c::Write<Error = E>,
+{
+    async fn read(&mut self, address: u8, read: &mut [u8]) -> Result<(), Self::Error> {
+        self.wrapped.read(address, read)
+    }
+
+    async fn write(&mut self, address: u8, write: &[u8]) -> Result<(), Self::Error> {
+        self.wrapped.write(address, write)
+    }
+
+    async fn write_read(&mut self, address: u8, write: &[u8], read: &mut [u8]) -> Result<(), Self::Error> {
+        self.wrapped.write_read(address, write, read)
+    }
+
+    async fn transaction(
+        &mut self,
+        address: u8,
+        operations: &mut [embedded_hal_1::i2c::Operation<'_>],
+    ) -> Result<(), Self::Error> {
+        let _ = address;
+        let _ = operations;
+        todo!()
+    }
+}
+
+//
+// SPI implementatinos
+//
+
+impl<T, E> embedded_hal_async::spi::ErrorType for BlockingAsync<T>
+where
+    E: embedded_hal_1::spi::Error,
+    T: blocking::spi::Transfer<u8, Error = E> + blocking::spi::Write<u8, Error = E>,
+{
+    type Error = E;
+}
+
+impl<T, E> embedded_hal_async::spi::SpiBus<u8> for BlockingAsync<T>
+where
+    E: embedded_hal_1::spi::Error + 'static,
+    T: blocking::spi::Transfer<u8, Error = E> + blocking::spi::Write<u8, Error = E>,
+{
+    async fn flush(&mut self) -> Result<(), Self::Error> {
+        Ok(())
+    }
+
+    async fn write(&mut self, data: &[u8]) -> Result<(), Self::Error> {
+        self.wrapped.write(data)?;
+        Ok(())
+    }
+
+    async fn read(&mut self, data: &mut [u8]) -> Result<(), Self::Error> {
+        self.wrapped.transfer(data)?;
+        Ok(())
+    }
+
+    async fn transfer(&mut self, read: &mut [u8], write: &[u8]) -> Result<(), Self::Error> {
+        // Ensure we write the expected bytes
+        for i in 0..core::cmp::min(read.len(), write.len()) {
+            read[i] = write[i].clone();
+        }
+        self.wrapped.transfer(read)?;
+        Ok(())
+    }
+
+    async fn transfer_in_place(&mut self, data: &mut [u8]) -> Result<(), Self::Error> {
+        self.wrapped.transfer(data)?;
+        Ok(())
+    }
+}
+
+/// NOR flash wrapper
+use embedded_storage::nor_flash::{ErrorType, MultiwriteNorFlash, NorFlash, ReadNorFlash};
+use embedded_storage_async::nor_flash::{
+    MultiwriteNorFlash as AsyncMultiwriteNorFlash, NorFlash as AsyncNorFlash, ReadNorFlash as AsyncReadNorFlash,
+};
+
+impl<T> ErrorType for BlockingAsync<T>
+where
+    T: ErrorType,
+{
+    type Error = T::Error;
+}
+
+impl<T> AsyncNorFlash for BlockingAsync<T>
+where
+    T: NorFlash,
+{
+    const WRITE_SIZE: usize = <T as NorFlash>::WRITE_SIZE;
+    const ERASE_SIZE: usize = <T as NorFlash>::ERASE_SIZE;
+
+    async fn write(&mut self, offset: u32, data: &[u8]) -> Result<(), Self::Error> {
+        self.wrapped.write(offset, data)
+    }
+
+    async fn erase(&mut self, from: u32, to: u32) -> Result<(), Self::Error> {
+        self.wrapped.erase(from, to)
+    }
+}
+
+impl<T> AsyncReadNorFlash for BlockingAsync<T>
+where
+    T: ReadNorFlash,
+{
+    const READ_SIZE: usize = <T as ReadNorFlash>::READ_SIZE;
+    async fn read(&mut self, address: u32, data: &mut [u8]) -> Result<(), Self::Error> {
+        self.wrapped.read(address, data)
+    }
+
+    fn capacity(&self) -> usize {
+        self.wrapped.capacity()
+    }
+}
+
+impl<T> AsyncMultiwriteNorFlash for BlockingAsync<T> where T: MultiwriteNorFlash {}

vendor/embassy-embedded-hal/src/adapter/mod.rs

@@ -0,0 +1,7 @@
+//! Adapters between embedded-hal traits.
+
+mod blocking_async;
+mod yielding_async;
+
+pub use blocking_async::BlockingAsync;
+pub use yielding_async::YieldingAsync;

vendor/embassy-embedded-hal/src/adapter/yielding_async.rs

@@ -0,0 +1,169 @@
+use embassy_futures::yield_now;
+
+/// Wrapper that yields for each operation to the wrapped instance
+///
+/// This can be used in combination with BlockingAsync<T> to enforce yields
+/// between long running blocking operations.
+pub struct YieldingAsync<T> {
+    wrapped: T,
+}
+
+impl<T> YieldingAsync<T> {
+    /// Create a new instance of a wrapper that yields after each operation.
+    pub fn new(wrapped: T) -> Self {
+        Self { wrapped }
+    }
+}
+
+//
+// I2C implementations
+//
+impl<T> embedded_hal_1::i2c::ErrorType for YieldingAsync<T>
+where
+    T: embedded_hal_1::i2c::ErrorType,
+{
+    type Error = T::Error;
+}
+
+impl<T> embedded_hal_async::i2c::I2c for YieldingAsync<T>
+where
+    T: embedded_hal_async::i2c::I2c,
+{
+    async fn read(&mut self, address: u8, read: &mut [u8]) -> Result<(), Self::Error> {
+        self.wrapped.read(address, read).await?;
+        yield_now().await;
+        Ok(())
+    }
+
+    async fn write(&mut self, address: u8, write: &[u8]) -> Result<(), Self::Error> {
+        self.wrapped.write(address, write).await?;
+        yield_now().await;
+        Ok(())
+    }
+
+    async fn write_read(&mut self, address: u8, write: &[u8], read: &mut [u8]) -> Result<(), Self::Error> {
+        self.wrapped.write_read(address, write, read).await?;
+        yield_now().await;
+        Ok(())
+    }
+
+    async fn transaction(
+        &mut self,
+        address: u8,
+        operations: &mut [embedded_hal_1::i2c::Operation<'_>],
+    ) -> Result<(), Self::Error> {
+        self.wrapped.transaction(address, operations).await?;
+        yield_now().await;
+        Ok(())
+    }
+}
+
+//
+// SPI implementations
+//
+
+impl<T> embedded_hal_async::spi::ErrorType for YieldingAsync<T>
+where
+    T: embedded_hal_async::spi::ErrorType,
+{
+    type Error = T::Error;
+}
+
+impl<T, Word: 'static + Copy> embedded_hal_async::spi::SpiBus<Word> for YieldingAsync<T>
+where
+    T: embedded_hal_async::spi::SpiBus<Word>,
+{
+    async fn flush(&mut self) -> Result<(), Self::Error> {
+        self.wrapped.flush().await?;
+        yield_now().await;
+        Ok(())
+    }
+
+    async fn write(&mut self, data: &[Word]) -> Result<(), Self::Error> {
+        self.wrapped.write(data).await?;
+        yield_now().await;
+        Ok(())
+    }
+
+    async fn read(&mut self, data: &mut [Word]) -> Result<(), Self::Error> {
+        self.wrapped.read(data).await?;
+        yield_now().await;
+        Ok(())
+    }
+
+    async fn transfer(&mut self, read: &mut [Word], write: &[Word]) -> Result<(), Self::Error> {
+        self.wrapped.transfer(read, write).await?;
+        yield_now().await;
+        Ok(())
+    }
+
+    async fn transfer_in_place(&mut self, words: &mut [Word]) -> Result<(), Self::Error> {
+        self.wrapped.transfer_in_place(words).await?;
+        yield_now().await;
+        Ok(())
+    }
+}
+
+///
+/// NOR flash implementations
+///
+impl<T: embedded_storage::nor_flash::ErrorType> embedded_storage::nor_flash::ErrorType for YieldingAsync<T> {
+    type Error = T::Error;
+}
+
+impl<T: embedded_storage_async::nor_flash::ReadNorFlash> embedded_storage_async::nor_flash::ReadNorFlash
+    for YieldingAsync<T>
+{
+    const READ_SIZE: usize = T::READ_SIZE;
+
+    async fn read(&mut self, offset: u32, bytes: &mut [u8]) -> Result<(), Self::Error> {
+        self.wrapped.read(offset, bytes).await?;
+        Ok(())
+    }
+
+    fn capacity(&self) -> usize {
+        self.wrapped.capacity()
+    }
+}
+
+impl<T: embedded_storage_async::nor_flash::NorFlash> embedded_storage_async::nor_flash::NorFlash for YieldingAsync<T> {
+    const WRITE_SIZE: usize = T::WRITE_SIZE;
+    const ERASE_SIZE: usize = T::ERASE_SIZE;
+
+    async fn write(&mut self, offset: u32, bytes: &[u8]) -> Result<(), Self::Error> {
+        self.wrapped.write(offset, bytes).await?;
+        yield_now().await;
+        Ok(())
+    }
+
+    async fn erase(&mut self, from: u32, to: u32) -> Result<(), Self::Error> {
+        // Yield between each actual erase
+        for from in (from..to).step_by(T::ERASE_SIZE) {
+            let to = core::cmp::min(from + T::ERASE_SIZE as u32, to);
+            self.wrapped.erase(from, to).await?;
+            yield_now().await;
+        }
+        Ok(())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use embedded_storage_async::nor_flash::NorFlash;
+
+    use super::*;
+    use crate::flash::mem_flash::MemFlash;
+
+    #[futures_test::test]
+    async fn can_erase() {
+        let flash = MemFlash::<1024, 128, 4>::new(0x00);
+        let mut yielding = YieldingAsync::new(flash);
+
+        yielding.erase(0, 256).await.unwrap();
+
+        let flash = yielding.wrapped;
+        assert_eq!(2, flash.erases.len());
+        assert_eq!((0, 128), flash.erases[0]);
+        assert_eq!((128, 256), flash.erases[1]);
+    }
+}