Create / Reset Admin User

This will create (or reset) the admin user with these credentials:

Username: admin
Password: admin123

Troubleshooting:

If you see "admins table does NOT exist" - import sql/database.sql in phpMyAdmin first.
If you see "Database connection failed" - check DB credentials in includes/config.php.
This script uses direct mysqli_query (no prepared statements) so it works on old PHP without mysqlnd driver.