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_production.py

@@ -42,7 +42,11 @@ def test_list_production_filters_by_scenario(client: TestClient) -> None:
     target_scenario = _create_scenario(client)
     other_scenario = _create_scenario(client)
 
-    for scenario_id, amount in [(target_scenario, 100.0), (target_scenario, 150.0), (other_scenario, 200.0)]:
+    for scenario_id, amount in [
+        (target_scenario, 100.0),
+        (target_scenario, 150.0),
+        (other_scenario, 200.0),
+    ]:
         response = client.post(
             "/api/production/",
             json={
@@ -57,8 +61,11 @@ def test_list_production_filters_by_scenario(client: TestClient) -> None:
 
     list_response = client.get("/api/production/")
     assert list_response.status_code == 200
-    items = [item for item in list_response.json()
-             if item["scenario_id"] == target_scenario]
+    items = [
+        item
+        for item in list_response.json()
+        if item["scenario_id"] == target_scenario
+    ]
     assert {item["amount"] for item in items} == {100.0, 150.0}