feat: implement full UPDATE.md review — critical fixes, UI upgrade, infra hardening

Critical frontend bugs:
- Add TrackSubscribed/attach() for agent audio playback
- Fix decodeToString TypeError with TextDecoder
- XSS fix: innerHTML -> textContent in addMessage
- Fresh token on reconnect retry

Agent fixes:
- GemmaLLM subclass with reasoning_content fallback wrapper
- Disable Gemma 4 thinking mode via chat_template_kwargs (6.8s -> 0.5s)
- Remove duplicate session-level LLM
- Replace global _active_session with closure-based handler
- asyncio.create_task instead of deprecated get_event_loop
- Explicit silero VAD, topic filter on voice-control

Infra:
- supervisord: all programs log to /dev/stdout
- Dockerfile: uv sync --frozen with committed uv.lock
- nginx config moved to real file, token_server.py no longer served
- entrypoint.sh: cert persisted, only regenerated on IP change
- compose: healthcheck + cert volume
- token_server: CORS removed, room pinned to voice-room

UI upgrade:
- Orb UI with state machine (idle/connecting/listening/thinking/speaking)
- Streaming transcripts via lk.transcription text streams
- Barge-in hint, thinking chip, audio visualizer
- Glassmorphism, chat bubbles, settings sheet, light mode
- PWA manifest, favicon, wake-lock, safe-area insets
- localStorage conversation history

Docs: AGENTS.md drift fixed

web/token_server.py

@@ -66,25 +66,17 @@ class Handler(BaseHTTPRequestHandler):
 
         length = int(self.headers.get("Content-Length", 0))
         body = json.loads(self.rfile.read(length) or b"{}")
-        room_name = body.get("room", "voice-room")
+        room_name = "voice-room"
         identity = body.get("identity") or f"user-{uuid.uuid4().hex[:8]}"
 
         token = make_token(room_name, identity)
         resp = json.dumps({"token": token}).encode()
         self.send_response(200)
         self.send_header("Content-Type", "application/json")
-        self.send_header("Access-Control-Allow-Origin", "*")
         self.send_header("Content-Length", str(len(resp)))
         self.end_headers()
         self.wfile.write(resp)
 
-    def do_OPTIONS(self):
-        self.send_response(204)
-        self.send_header("Access-Control-Allow-Origin", "*")
-        self.send_header("Access-Control-Allow-Methods", "POST, OPTIONS")
-        self.send_header("Access-Control-Allow-Headers", "Content-Type")
-        self.end_headers()
-
     def log_message(self, format, *args):
         pass  # silence request logging