feat(ui-core,ui-lvgl): sound in the Core, L2 speaker via ES8311, Sound settings, melody editor

- genericBuzzer I2S path (BUZZER_I2S): an audio task synthesises the notes
  with eased edges and keeps the DMA queue fed with silence between sounds;
  ES8311 setup; amp powered through the board only around sounds
- ui-core/SoundControl.h (mode, volume, built-in sounds, melody model),
  SoundNotifier moved to the Core, chanctl::melody, schema Sound page
- L2: notifications, alarm / timer ring, locator sounds, Settings > Sound,
  melody editor with the playing note lit, per-chat sound, mute icon
- noteIndex() on every buzzer backend; scrolling popups past screen height

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

variants/wio-tracker-l2/target.cpp

@@ -18,6 +18,10 @@ EnvironmentSensorManager sensors(gps);
   MomentaryButton user_btn(PIN_USER_BTN, 1000, true, true);
 #endif
 
+#ifdef BUZZER_I2S
+void buzzerAmpPower(bool on) { board.setSpeakerAmp(on); }
+#endif
+
 bool radio_init() {
   MESH_DEBUG_PRINTLN("radio_init: rtc + sx1262 init");
   fallback_clock.begin();