fix: compute correct LiveKit room name hash for Element Call

Element Call uses SHA256(room_id + "|m.call#ROOM") encoded as unpadded
base64 for LiveKit room names (via lk-jwt-service). The bot was using
the raw Matrix room ID, causing agent and user to join different rooms.

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

bot.py

@@ -2,6 +2,7 @@ import os
 import json
 import asyncio
 import base64
+import hashlib
 import io
 import logging
 import re
@@ -389,13 +390,11 @@ class Bot:
                 "livekit_alias": room_id,
             }])
 
-            # Extract LiveKit room name from foci and dispatch agent
-            lk_room_name = room_id  # fallback
-            for f in foci:
-                if f.get("type") == "livekit" and f.get("livekit_alias"):
-                    lk_room_name = f["livekit_alias"]
-                    break
-            logger.info("LiveKit room name: %s (from foci_preferred)", lk_room_name)
+            # Compute LiveKit room name using same hash as lk-jwt-service
+            # SHA256(room_id + "|" + "m.call#ROOM") encoded as unpadded base64
+            lk_room_hash = hashlib.sha256((room_id + "|m.call#ROOM").encode()).digest()
+            lk_room_name = base64.b64encode(lk_room_hash).decode().rstrip("=")
+            logger.info("LiveKit room name: %s (hashed from %s)", lk_room_name, room_id)
 
             if room_id not in self.dispatched_rooms:
                 try: