✨(audio) assign users to diarization speaker results using VAD

Introduce a new user assignment mechanism to for more friendly output
than the current (SPEAKER_0, SPEAKER_1, ...). Use the VAD metadata to
compare speech intervals with those returned by WhisperX. User with the
highest overlap score above a defined threshold is assigned to each segment.
This method allows for multi-speaker scenarios for a single account.

src/backend/core/api/viewsets.py

@@ -363,6 +363,7 @@ class RoomViewSet(
         ):
             try:
                 MetadataCollectorService().start(recording)
+                logger.debug("Started MetadataCollectorService")
             except MetadataCollectorException:
                 logger.warning("Failed to start MetadataCollectorService")