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/simulation.py

@@ -25,12 +25,13 @@ def _ensure_positive_span(span: float, fallback: float) -> float:
     return span if span and span > 0 else fallback
 
 
-def _compile_parameters(parameters: Sequence[Dict[str, float]]) -> List[SimulationParameter]:
+def _compile_parameters(
+    parameters: Sequence[Dict[str, float]],
+) -> List[SimulationParameter]:
     compiled: List[SimulationParameter] = []
     for index, item in enumerate(parameters):
         if "value" not in item:
-            raise ValueError(
-                f"Parameter at index {index} must include 'value'")
+            raise ValueError(f"Parameter at index {index} must include 'value'")
         name = str(item.get("name", f"param_{index}"))
         base_value = float(item["value"])
         distribution = str(item.get("distribution", "normal")).lower()
@@ -43,8 +44,11 @@ def _compile_parameters(parameters: Sequence[Dict[str, float]]) -> List[Simulati
 
         if distribution == "normal":
             std_dev = item.get("std_dev")
-            std_dev_value = float(std_dev) if std_dev is not None else abs(
-                base_value) * DEFAULT_STD_DEV_RATIO or 1.0
+            std_dev_value = (
+                float(std_dev)
+                if std_dev is not None
+                else abs(base_value) * DEFAULT_STD_DEV_RATIO or 1.0
+            )
             compiled.append(
                 SimulationParameter(
                     name=name,