fix: unique room names per session, JT_ROOM dispatch, dispatch-first prompt

- token_server: generate voice-{uuid8} room name per request so each
  browser session creates a fresh room and triggers agent dispatch
- token claim: add jobType JT_ROOM to roomConfig.agents
- livekit.yaml: revert empty_timeout to default (300s)
- agent.py: system prompt now mandates dispatch_task for all non-trivial
  tasks (not just research); removed inline web_search instructions;
  added tool_call logging in _ReasoningFallbackWrapper

livekit.yaml

@@ -7,9 +7,5 @@ rtc:
 keys:
   devkey: devsecret
 
-# Keep rooms alive for 24h — the agent stays resident so reconnections
-# don't require a fresh dispatch. Without this, LiveKit destroys the room
-# after empty_timeout (default 300s), kills the agent job, and the next
-# join finds no worker registered ("assistant not ready retry").
-room:
-  empty_timeout: 86400
+# Rooms are short-lived: each browser session gets a unique room name, so
+# the agent is dispatched at room creation. Default 300s cleanup is fine.