🐛(backend) preserve recording metadata when updating room access

Updating room access rewrote the entire metadata payload, removing information
about active recordings. This caused the frontend to lose track of ongoing
recordings and could trigger 409 errors when attempting to start a new
recording.

Consolidate the duplicated metadata update logic into
`RoomManagement.update_metadata()` and preserve merge behavior instead of
overwriting the full metadata object.

src/backend/core/services/livekit_events.py

@@ -11,7 +11,7 @@ from django.conf import settings
 
 from livekit import api
 
-from core import models, utils
+from core import models
 from core.recording.services.metadata_collector import (
     MetadataCollectorException,
     MetadataCollectorService,
@@ -23,6 +23,11 @@ from core.recording.services.recording_events import (
 )
 
 from .lobby import LobbyService
+from .room_management import (
+    RoomManagement,
+    RoomManagementException,
+    RoomNotFoundException,
+)
 from .telephony import TelephonyException, TelephonyService
 
 logger = getLogger(__name__)
@@ -177,10 +182,15 @@ class LiveKitEventsService:
 
         try:
             room_name = str(recording.room.id)
-            utils.update_room_metadata(
-                room_name, {}, ["recording_mode", "recording_status"]
+            RoomManagement().update_metadata(
+                room_name, remove_keys=["recording_mode", "recording_status"]
             )
-        except utils.MetadataUpdateException as e:
+        except RoomNotFoundException:
+            logger.info(
+                "LiveKit room %s no longer exists, skipping metadata update",
+                room_name,
+            )
+        except RoomManagementException as e:
             logger.exception("Failed to update room's metadata: %s", e)
 
         if recording.options.get("metadata_collector_dispatch_id", None) is not None: