Refactor test cases for improved readability and consistency

- Updated test functions in various test files to enhance code clarity by formatting long lines and improving indentation.
- Adjusted assertions to use multi-line formatting for better readability.
- Added new test cases for theme settings API to ensure proper functionality.
- Ensured consistent use of line breaks and spacing across test files for uniformity.

tests/unit/test_parameters.py

@@ -67,7 +67,10 @@ def test_create_and_list_parameter():
 
 def test_create_parameter_for_missing_scenario():
     payload: Dict[str, Any] = {
-        "scenario_id": 0, "name": "invalid", "value": 1.0}
+        "scenario_id": 0,
+        "name": "invalid",
+        "value": 1.0,
+    }
     response = client.post("/api/parameters/", json=payload)
     assert response.status_code == 404
     assert response.json()["detail"] == "Scenario not found"