Improve SignalWire streaming, randomize caller names, update frontend

- Add streamSid tracking and per-caller send locks for SignalWire
- Improve TTS streaming with real-time pacing and detailed logging
- Block host audio to caller during TTS playback
- Randomize caller names between sessions from name pools
- Update page title and show phone number in UI

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

audio_settings.json

@@ -3,6 +3,7 @@
   "input_channel": 1,
   "output_device": 13,
   "caller_channel": 3,
+  "live_caller_channel": 9,
   "music_channel": 5,
   "sfx_channel": 7,
   "phone_filter": false