fix(rgbled): double-buffer WS2812 strip to eliminate races (#7304)

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

radio/src/targets/pl18/board.cpp

@@ -21,7 +21,6 @@
  
 #include "stm32_adc.h"
 #include "stm32_gpio.h"
-#include "stm32_ws2812.h"
 #include "stm32_spi.h"
 
 #include "hal/adc_driver.h"
@@ -139,15 +138,9 @@ void delay_self(int count)
 }
 
 #if defined(LED_STRIP_GPIO)
-// Common LED driver
-extern const stm32_pulse_timer_t _led_timer;
-
 void ledStripOff()
 {
-  for (uint8_t i = 0; i < LED_STRIP_LENGTH; i++) {
-    ws2812_set_color(i, 0, 0, 0);
-  }
-  ws2812_update(&_led_timer);
+  rgbLedClearAll();
 }
 #endif