fix(e2ee): use set_shared_key for live key rotation updates

When Element Call sees the bot join, it rotates its encryption key
(index 0 → 1). The on_encryption_key callback was calling set_key()
(per-participant) which has no effect in shared-key mode. Switch to
set_shared_key() so the shared-key decryption path stays current when
the caller rotates keys.

voice.py

@@ -116,15 +116,15 @@ class VoiceSession:
         self._caller_all_keys[index] = key
         logger.info("E2EE key received from %s:%s (index=%d, %d bytes)",
                     sender, device_id, index, len(key))
-        # Live-update key provider if already connected
+        # Live-update shared key when caller rotates (e.g. on bot join) — use
+        # set_shared_key so the shared-key decryption path stays in sync.
         if self.lk_room and hasattr(self.lk_room, 'e2ee_manager'):
             try:
                 kp = self.lk_room.e2ee_manager.key_provider
-                caller_id = self._caller_identity or f"{sender}:{device_id}"
-                kp.set_key(caller_id, key, index)
-                logger.info("Live-set caller key[%d] for %s", index, caller_id)
+                kp.set_shared_key(key, index)
+                logger.info("Live-updated shared key[%d] (%d bytes)", index, len(key))
             except Exception as e:
-                logger.warning("Failed to live-set caller key: %s", e)
+                logger.warning("Failed to live-update shared key: %s", e)
 
     async def _fetch_encryption_key_http(self) -> bytes | None:
         """Fetch encryption key from room timeline (NOT state) via Matrix HTTP API.