Refactor(backend): improve formatting in services, repositories & tests

- Consistently format multi-line function headers, exception handling, and repository method calls for readability.
- Reorganize misplaced imports across modules (e.g., services & tests) into proper sorted order.
- Adjust indentation, line breaks, and spacing inconsistencies in tests and migration files.
- Cleanup unnecessary trailing newlines and reorganize `__all__` declarations for consistency.

backend/app/services/__init__.py

@@ -9,11 +9,11 @@ from .user_service import UserService, user_service
 __all__ = [
     "AuthService",
     "OAuthService",
-    "UserService",
     "OrganizationService",
     "SessionService",
+    "UserService",
     "oauth_provider_service",
-    "user_service",
     "organization_service",
     "session_service",
+    "user_service",
 ]