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/e2e/test_scenarios.py

@@ -39,4 +39,5 @@ def test_create_new_scenario(page: Page):
     feedback = page.locator("#feedback")
     expect(feedback).to_be_visible()
     expect(feedback).to_have_text(
-        f'Scenario "{scenario_name}" created successfully.')
+        f'Scenario "{scenario_name}" created successfully.'
+    )