test: remediate and stabilize auxiliary backend and frontend tests

- Standardized task log, LLM provider, and report profile tests.
- Relocated auxiliary tests into __tests__ directories for consistency.
- Updated git_service and defensive guards with minor stability fixes discovered during testing.
- Added UX integration tests for the reports list component.

backend/src/scripts/test_dataset_dashboard_relations.py

@@ -100,7 +100,10 @@ def test_dashboard_dataset_relations():
                 logger.info(f"  Found {len(dashboards)} dashboards using this dataset:")
                 
                 for dash in dashboards:
-                    logger.info(f"    - Dashboard ID {dash.get('id')}: {dash.get('dashboard_title', dash.get('title', 'Unknown'))}")
+                    if isinstance(dash, dict):
+                        logger.info(f"    - Dashboard ID {dash.get('id')}: {dash.get('dashboard_title', dash.get('title', 'Unknown'))}")
+                    else:
+                        logger.info(f"    - Dashboard: {dash}")
             elif 'result' in related_objects:
                 # Some Superset versions use 'result' wrapper
                 result = related_objects['result']