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_production.py

@@ -43,5 +43,6 @@ def test_create_production_item(page: Page):
     ).to_be_visible()
 
     # Verify the feedback message.
-    expect(page.locator("#production-feedback")
-           ).to_have_text("Production output saved.")
+    expect(page.locator("#production-feedback")).to_have_text(
+        "Production output saved."
+    )