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_consumption.py

@@ -57,8 +57,11 @@ def test_list_consumption_returns_created_items(client: TestClient) -> None:
 
     list_response = client.get("/api/consumption/")
     assert list_response.status_code == 200
-    items = [item for item in list_response.json(
-    ) if item["scenario_id"] == scenario_id]
+    items = [
+        item
+        for item in list_response.json()
+        if item["scenario_id"] == scenario_id
+    ]
     assert {item["amount"] for item in items} == set(values)