fix(wio-tracker-l2): radios and codec idle when unused; buzzer and OTA fixes

- BLE (ESP32): fast advertising (20-30 ms) for 30 s, then 152.5 ms, as the
  nRF52 interface; the library default kept 30-60 ms forever
- Live map tiles: the WiFi drops after a minute with nothing missing
- ES8311 to standby while the I2S clocks are off, set up again before the
  amp comes on
- Buzzer: no channel (DMA out of memory) waits out the samples instead of
  spinning above the UI loop
- OTA: the image header check waits for its 16 bytes
- Comments: P10 is just the LED; the LCD SPI clock is 40 MHz on the wire

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

variants/wio-tracker-l2/WioTrackerL2Board.cpp

@@ -158,8 +158,7 @@ void WioTrackerL2Board::begin() {
 }
 
 void WioTrackerL2Board::setLed(bool on) {
-  // P10 doubles as GNSS wakeup and idles HIGH; blink = brief LOW pulses so
-  // the GPS never sees a sustained low level
+  // active low: HIGH = off
   if (expander_ok) {
     expWritePin(EXP_PIN_USER_LED, !on);
   }