Add internet radio streaming with runtime API, modernize web UI, remove auto-tune/beep at boot

Streaming (main feature this session):
- New WebRadioConfig/WebRadioJson core types, ISecureStore-backed persistence
- New webradio::WebRadioService (thread-safe live config) + GET/POST /api/streaming
- web_radio_stream task now runtime-toggleable (no reboot), no hardcoded URL
- Content-Type diagnostic: warns clearly when a URL is a webpage, not an audio stream

Boot cleanup:
- Removed boot-time auto FM/DAB tune, auto-beep, and the (now-concluded) Si4684
  crystal IBIAS/CTUN empirical sweep from main.cpp — tuning/beep are on-demand
  via the existing REST API only

Web UI:
- Modernized styling (cards, gradients, toggle switches, light/dark theme)
- New Stream tab wired to /api/streaming

Fixes found via real idf.py build (not just clangd):
- Restored wrongly-removed si4684/Si4684Tuner.hpp include in main.cpp
- Fixed MP3Decode() argument types in web_radio_stream.cpp (unsigned char**/int*)

Quality-gate fixes:
- Host-test stub headers (esp_log.h, freertos/*) so TunerService.cpp's
  scanForStation logging/pacing compiles for station_service_test /
  integration_service_test instead of running stale binaries
- Added WifiScanner and WebRadioService manual sections; filled in missing
  Doxygen docs on BluetoothService, i2s_sdata_probe, test_firmware, Bt1035At
- Ignore clangd's .cache/ index directory

Also includes prior uncommitted work carried in the tree: Wi-Fi/Bluetooth
device scan REST API and UI (WifiScanner, BT scan), SigmaStudio TCP bridge,
and the current ADAU1701 SigmaStudio DSP program export.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

Software/main/test_firmware.cpp

@@ -124,8 +124,6 @@ void runTestFirmware()
         bt1035::Bt1035Pins{
             .uartTx = board::pins::Bt1035UartTx,
             .uartRx = board::pins::Bt1035UartRx,
-            .rtsGpio = board::pins::Bt1035Rts,
-            .ctsGpio = board::pins::Bt1035Cts,
             .resetGpio = board::pins::Bt1035Reset,
             .sysCtlGpio = board::pins::Bt1035SysCtl,
         });
@@ -178,9 +176,12 @@ void runTestFirmware()
 
     if (auto rsqResult = si4684.readFmRsq(); rsqResult) {
         ESP_LOGI(kTag,
-                 "FM RSQ: snr=%u, afc=%d, blend=%u, stere=%u, rssi=%d",
-                 rsqResult->snr, rsqResult->afc, rsqResult->blend,
-                 rsqResult->stere, rsqResult->rssi);
+                 "FM RSQ: freq=%u kHz rssi=%d dBuV snr=%d dB valid=%d stereo=%d",
+                 rsqResult->frequency ? rsqResult->frequency->value() : 0U,
+                 static_cast<int>(rsqResult->rssiDbuV),
+                 static_cast<int>(rsqResult->snrDb),
+                 static_cast<int>(rsqResult->valid),
+                 static_cast<int>(rsqResult->stereo));
     } else {
         logError("Si4684 read FM RSQ", static_cast<int>(rsqResult.error()));
     }