test(backend): add comprehensive tests for OAuth and agent endpoints

- Added tests for OAuth provider admin and consent endpoints covering edge cases.
- Extended agent-related tests to handle incorrect project associations and lifecycle state transitions.
- Introduced tests for sprint status transitions and validation checks.
- Improved multiline formatting consistency across all test functions.

backend/tests/api/routes/test_events.py

@@ -274,7 +274,11 @@ class TestSSEEndpointStream:
 
     @pytest.mark.asyncio
     async def test_stream_events_with_events(
-        self, client_with_mock_bus, user_token_with_mock_bus, mock_event_bus, test_project_for_events
+        self,
+        client_with_mock_bus,
+        user_token_with_mock_bus,
+        mock_event_bus,
+        test_project_for_events,
     ):
         """Test that SSE endpoint yields events."""
         project_id = test_project_for_events.id
@@ -361,7 +365,11 @@ class TestTestEventEndpoint:
 
     @pytest.mark.asyncio
     async def test_send_test_event_success(
-        self, client_with_mock_bus, user_token_with_mock_bus, mock_event_bus, test_project_for_events
+        self,
+        client_with_mock_bus,
+        user_token_with_mock_bus,
+        mock_event_bus,
+        test_project_for_events,
     ):
         """Test sending a test event."""
         project_id = test_project_for_events.id