fix(CF-1170): Fix STT by correcting agent dispatch flow

Three fixes for voice agent not responding to speech:
1. Agent name: add --agent-name matrix-ai to CLI (was empty, dispatch couldnt match)
2. Move dispatch from on_invite to on_unknown call handler (dispatch when call starts, not on room join)
3. Use LiveKit room name from foci_preferred instead of raw Matrix room ID

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

docker-compose.yml

@@ -1,7 +1,7 @@
 services:
   agent:
     build: .
-    command: python agent.py start
+    command: python agent.py start --agent-name matrix-ai
     env_file: .env
     restart: unless-stopped
     network_mode: host