✨(backend) add dedicated service for LiveKit recording webhook events

Create new service to handle recording-related webhooks, starting with
limit reached events. Will expand to enhance UX by notifying backend
of other LiveKit events.

Doesn't fit cleanly with existing recording package - may need broader
redesign. Chose dedicated service over mixing responsibilities.

src/backend/core/tests/recording/service/test_recording_events.py

@@ -0,0 +1,72 @@
+"""
+Test RecordingEventsService service.
+"""
+
+# pylint: disable=W0621
+
+from unittest import mock
+
+import pytest
+
+from core.factories import RecordingFactory
+from core.recording.services.recording_events import (
+    RecordingEventsError,
+    RecordingEventsService,
+)
+from core.utils import NotificationError
+
+pytestmark = pytest.mark.django_db
+
+
+@pytest.fixture
+def service():
+    """Initialize RecordingEventsService."""
+    return RecordingEventsService()
+
+
+@pytest.mark.parametrize(
+    ("mode", "notification_type"),
+    (
+        ("screen_recording", "screenRecordingLimitReached"),
+        ("transcript", "transcriptionLimitReached"),
+    ),
+)
+@mock.patch("core.utils.notify_participants")
+def test_handle_limit_reached_success(mock_notify, mode, notification_type, service):
+    """Test handle_limit_reached stops recording and notifies participants."""
+
+    recording = RecordingFactory(status="active", mode=mode)
+    service.handle_limit_reached(recording)
+
+    assert recording.status == "stopped"
+    mock_notify.assert_called_once_with(
+        room_name=str(recording.room.id), notification_data={"type": notification_type}
+    )
+
+
+@pytest.mark.parametrize(
+    ("mode", "notification_type"),
+    (
+        ("screen_recording", "screenRecordingLimitReached"),
+        ("transcript", "transcriptionLimitReached"),
+    ),
+)
+@mock.patch("core.utils.notify_participants")
+def test_handle_limit_reached_error(mock_notify, mode, notification_type, service):
+    """Test handle_limit_reached raises RecordingEventsError when notification fails."""
+
+    mock_notify.side_effect = NotificationError("Error notifying")
+
+    recording = RecordingFactory(status="active", mode=mode)
+
+    with pytest.raises(
+        RecordingEventsError,
+        match=r"Failed to notify participants in room '.+' "
+        r"about recording limit reached \(recording_id=.+\)",
+    ):
+        service.handle_limit_reached(recording)
+
+    assert recording.status == "stopped"
+    mock_notify.assert_called_once_with(
+        room_name=str(recording.room.id), notification_data={"type": notification_type}
+    )