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.

scripts/migrations/20251027_create_theme_settings_table.sql

@@ -0,0 +1,11 @@
+-- Migration: 20251027_create_theme_settings_table.sql
+
+CREATE TABLE theme_settings (
+    id SERIAL PRIMARY KEY,
+    theme_name VARCHAR(255) UNIQUE NOT NULL,
+    primary_color VARCHAR(7) NOT NULL,
+    secondary_color VARCHAR(7) NOT NULL,
+    accent_color VARCHAR(7) NOT NULL,
+    background_color VARCHAR(7) NOT NULL,
+    text_color VARCHAR(7) NOT NULL
+);