refactor: clean up imports and improve db_session fixture in test configuration

app/database.py

@@ -64,4 +64,4 @@ async def get_test_db() -> AsyncGenerator:
             # Only log actual database-related issues, not response validation
             if not isinstance(ex, ResponseValidationError):
                 await logger.aerror(f"Database-related error: {repr(ex)}")
-            raise  # Re-raise to be handled by appropriate handlers
+            raise  # Re-raise to be handled by appropriate handlers