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/api/routes/auth.py

@@ -429,9 +429,7 @@ async def confirm_password_reset(
                 raise HTTPException(
                     status_code=status.HTTP_400_BAD_REQUEST, detail=err_msg
                 )
-            raise HTTPException(
-                status_code=status.HTTP_404_NOT_FOUND, detail=err_msg
-            )
+            raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail=err_msg)
 
         # SECURITY: Invalidate all existing sessions after password reset
         # This prevents stolen sessions from being used after password change