fix: Wio Tracker LED on P1.01, move SimpleLed to board layer

Per the Wio Tracker L1 schematic, it has a green LED on P1.01.
Moved SimpleLed from driver/ to board layer (esp32s3.rs and
wio_tracker_l1.rs) since the impl needs HAL-specific Output types.
Removed driver/simple_led.rs — each board layer defines its own.
RAK WisBlock remains LedDriver=() (no user LED on the core module).

src/driver/mod.rs

@@ -1,5 +1,2 @@
 #[cfg(feature = "wio_tracker_l1")]
 pub mod sh1106;
-
-#[cfg(any(feature = "heltec_v3", feature = "heltec_v3_uart", feature = "heltec_v4"))]
-pub mod simple_led;

src/driver/simple_led.rs

@@ -1,28 +0,0 @@
-//! Simple single-color LED driver (GPIO on/off).
-//!
-//! For boards with a plain LED (not addressable RGB). Any non-zero
-//! RGB value turns the LED on; all zeros turns it off.
-
-use esp_hal::gpio::Output;
-
-use crate::board::RgbLed;
-
-pub struct SimpleLed {
-    pin: Output<'static>,
-}
-
-impl SimpleLed {
-    pub fn new(pin: Output<'static>) -> Self {
-        Self { pin }
-    }
-}
-
-impl RgbLed for SimpleLed {
-    async fn set_rgb(&mut self, r: u8, g: u8, b: u8) {
-        if r > 0 || g > 0 || b > 0 {
-            self.pin.set_high();
-        } else {
-            self.pin.set_low();
-        }
-    }
-}