🔧(frontend) pass recording max duration to frontend for user alerts

Send backend recording duration limit to frontend to display warning
messages when recordings approach or reach maximum allowed length.

This configuration needs to be synced with the egres. I chose to keep
this duration in ms to be consistent with other settings.

src/backend/core/api/__init__.py

@@ -41,6 +41,7 @@ def get_frontend_configuration(request):
             "is_enabled": settings.RECORDING_ENABLE,
             "available_modes": settings.RECORDING_WORKER_CLASSES.keys(),
             "expiration_days": settings.RECORDING_EXPIRATION_DAYS,
+            "max_duration": settings.RECORDING_MAX_DURATION,
         },
         "telephony": {
             "enabled": settings.ROOM_TELEPHONY_ENABLED,