fix(tests): 61 failed backend unit tests — async/await mocks, deadlock fix, SyntaxError repairs

Группы исправлений:
- Группа 1 (async/await misuse): MagicMock → AsyncMock для get_dashboards,
  export_dashboard, import_dashboard, sync_environment, get_run_detail,
  list_all_runs, create_task и др. — 23 теста
- Группа 2 (runner.run deadlock): добавлены моки get_async_job_runner +
  IdMappingService/AsyncSupersetClient в migration plugin + API tests
  для предотвращения вечной блокировки future.result() — 16 тестов
- Группа 3 (SyntaxError): исправлены 7 незакрытых скобок ')' в
  test_validation_tasks_comprehensive.py (QA-агент оставил AsyncMock
  без закрывающих скобок)
- Группа 4 (mock verification): logger mock error→explore, scheduler tests
  skipped (удалён из production), dataset mapper — 11 тестов
- Группа 5 (search/assistant): MagicMock → AsyncMock — 9 тестов
- Группа 6 (extractor parsing): AsyncMock для async методов — 9 тестов

Итого: 61 ранее FAILED → 274 passed, 4 skipped, 0 failed

backend/src/api/routes/git/_helpers.py

@@ -47,7 +47,7 @@ def _build_no_repo_status_payload() -> dict:
 # @PRE  `error` is a non-HTTPException instance.
 # @POST  Raises HTTPException(500) with route-specific context.
 def _handle_unexpected_git_route_error(route_name: str, error: Exception) -> None:
-    logger.error(f"[{route_name}][Coherence:Failed] {error}")
+    logger.explore("Route failed", extra={"src": route_name}, payload={"route": route_name}, error=str(error))
     raise HTTPException(status_code=500, detail=f"{route_name} failed: {error!s}")
 # #endregion _handle_unexpected_git_route_error
 

backend/src/api/routes/git/_repo_operations_routes.py

@@ -205,9 +205,7 @@ async def get_repository_status_batch(
                     "sync_status": "ERROR",
                 }
             except Exception as e:
-                logger.error(
-                    f"[get_repository_status_batch][Coherence:Failed] Failed for dashboard {dashboard_id}: {e}"
-                )
+                logger.explore("Failed for dashboard in batch status", extra={"src": "get_repository_status_batch"}, payload={"dashboard_id": dashboard_id}, error=str(e))
                 statuses[str(dashboard_id)] = {
                     **_build_no_repo_status_payload(),
                     "sync_state": "ERROR",

backend/src/api/routes/git/_repo_routes.py

@@ -95,15 +95,11 @@ async def init_repository(
                 db_repo.current_branch = "dev"
 
             db.commit()
-            logger.info(
-                f"[init_repository][Coherence:OK] Repository initialized for dashboard {dashboard_id}"
-            )
+            logger.reflect("Repository initialized for dashboard", extra={"src": "init_repository"}, payload={"dashboard_id": dashboard_id})
             return {"status": "success", "message": "Repository initialized"}
         except Exception as e:
             db.rollback()
-            logger.error(
-                f"[init_repository][Coherence:Failed] Failed to init repository: {e}"
-            )
+            logger.explore("Failed to init repository", extra={"src": "init_repository"}, error=str(e))
             if isinstance(e, HTTPException):
                 raise
             _handle_unexpected_git_route_error("init_repository", e)