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>

src/helpers/ui/ES8311.h

@@ -0,0 +1,45 @@
+#pragma once
+// Minimal Everest ES8311 mono codec setup for tone playback: DAC only, I2S
+// slave, 16-bit, the host supplies MCLK = 256 x fs. Register values follow
+// Espressif's esp-adf es8311 driver, with its clock coefficients for MCLK
+// 4.096 MHz / fs 16 kHz folded in.
+
+#include <Arduino.h>
+#include <Wire.h>
+
+namespace es8311 {
+
+static bool write(TwoWire& w, uint8_t addr, uint8_t reg, uint8_t val) {
+  w.beginTransmission(addr);
+  w.write(reg);
+  w.write(val);
+  return w.endTransmission() == 0;
+}
+
+// Codec on and playing whatever arrives on I2S. False: no codec at `addr`.
+static bool begin(TwoWire& w, uint8_t addr) {
+  static const uint8_t SEQ[][2] = {
+    { 0x45, 0x00 }, { 0x01, 0x30 }, { 0x02, 0x00 }, { 0x03, 0x10 }, { 0x16, 0x24 },
+    { 0x04, 0x10 }, { 0x05, 0x00 }, { 0x0B, 0x00 }, { 0x0C, 0x00 }, { 0x10, 0x1F },
+    { 0x11, 0x7F },
+    { 0x00, 0x80 },   // power up the state machine, slave mode
+    { 0x01, 0x3F },   // MCLK from its pin, every clock on
+    // fs = MCLK / 256: pre-divider / multiplier 1, ADC / DAC dividers 1,
+    // single-speed, OSR 0x10, LRCK divider 0x0FF, BCLK divider 4
+    { 0x02, 0x00 }, { 0x05, 0x00 }, { 0x03, 0x10 }, { 0x04, 0x10 },
+    { 0x07, 0x00 }, { 0x08, 0xFF }, { 0x06, 0x03 },
+    { 0x13, 0x10 }, { 0x1B, 0x0A }, { 0x1C, 0x6A },
+    { 0x09, 0x0C },   // DAC serial port: I2S, 16-bit, unmuted
+    { 0x0A, 0x0C },   // ADC serial port: the same (unused)
+    // start: analog up, DAC powered, output driver on
+    { 0x17, 0xBF }, { 0x0E, 0x02 }, { 0x12, 0x00 }, { 0x14, 0x1A }, { 0x0D, 0x01 },
+    { 0x15, 0x40 }, { 0x37, 0x08 }, { 0x45, 0x00 },
+    { 0x32, 0xBF },   // DAC volume 0 dB (the player scales its samples)
+    { 0x31, 0x00 },   // DAC unmuted
+  };
+  for (size_t i = 0; i < sizeof(SEQ) / sizeof(SEQ[0]); i++)
+    if (!write(w, addr, SEQ[i][0], SEQ[i][1])) return false;
+  return true;
+}
+
+}  // namespace es8311