✨(backend) add two new endpoints to start and stop a recording

The LiveKit egress worker interactions are proxied through the backend for
security reasons. Allowing clients to directly use tokens with sufficient
grants to start recordings could lead to misuse, enabling users to spam the
egress worker API and potentially initiate a DDOS attack on the egress
service. To prevent this, only users with room-specific privileges can
initiate recordings.

We make sure only one recording at the time can be made on a room.

The requested recording mode is stored so it can be referenced later when
the recording is saved, triggering a callback action as needed.

A feature flag was also introduced for this capability; while this is a simple
approach, a more robust system for managing feature flags could be valuable
long-term. For now, KISS (Keep It Simple, Stupid) applies.

The viewset endpoints were designed to be as straightforward as possible—
let me know if anything can be improved.

src/backend/core/api/permissions.py

@@ -1,5 +1,7 @@
 """Permission handlers for the Meet core app."""
 
+from django.conf import settings
+
 from rest_framework import permissions
 
 from ..models import RoleChoices
@@ -87,3 +89,23 @@ class HasAbilityPermission(IsAuthenticated):
     def has_object_permission(self, request, view, obj):
         """Check permission for a given object."""
         return obj.get_abilities(request.user).get(view.action, False)
+
+
+class HasPrivilegesOnRoom(IsAuthenticated):
+    """Check if user has privileges on a given room."""
+
+    message = "You must have privileges to start a recording."
+
+    def has_object_permission(self, request, view, obj):
+        """Determine if user has privileges on room."""
+        return obj.is_owner(request.user) or obj.is_administrator(request.user)
+
+
+class IsRecordingEnabled(permissions.BasePermission):
+    """Check if the recording feature is enabled."""
+
+    message = "Access denied, recording is disabled."
+
+    def has_permission(self, request, view):
+        """Determine if access is allowed based on settings."""
+        return settings.RECORDING_ENABLE