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_user_and_role_tables.sql

@@ -0,0 +1,15 @@
+-- Migration: 20251027_create_user_and_role_tables.sql
+
+CREATE TABLE roles (
+    id SERIAL PRIMARY KEY,
+    name VARCHAR(255) UNIQUE NOT NULL
+);
+
+CREATE TABLE users (
+    id SERIAL PRIMARY KEY,
+    username VARCHAR(255) UNIQUE NOT NULL,
+    email VARCHAR(255) UNIQUE NOT NULL,
+    hashed_password VARCHAR(255) NOT NULL,
+    role_id INTEGER NOT NULL,
+    FOREIGN KEY (role_id) REFERENCES roles(id)
+);