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.

services/reporting.py

@@ -27,7 +27,9 @@ def _percentile(values: List[float], percentile: float) -> float:
     return sorted_values[lower] * (1 - weight) + sorted_values[upper] * weight
 
 
-def generate_report(simulation_results: List[Dict[str, float]]) -> Dict[str, Union[float, int]]:
+def generate_report(
+    simulation_results: List[Dict[str, float]],
+) -> Dict[str, Union[float, int]]:
     """Aggregate basic statistics for simulation outputs."""
 
     values = _extract_results(simulation_results)
@@ -63,7 +65,7 @@ def generate_report(simulation_results: List[Dict[str, float]]) -> Dict[str, Uni
 
     std_dev = pstdev(values) if len(values) > 1 else 0.0
     summary["std_dev"] = std_dev
-    summary["variance"] = std_dev ** 2
+    summary["variance"] = std_dev**2
 
     var_95 = summary["percentile_5"]
     summary["value_at_risk_95"] = var_95