phpMyFAQ has unauthenticated config backup download via /api/setup/backup

phpMyFAQ is an open source FAQ web application. In versions prior to 4.0.16, an unauthenticated remote attacker can trigger generation of a configuration backup ZIP via `POST /api/setup/backup` and then download the generated ZIP from a web-accessible location. The ZIP contains sensitive configuration files (e.g., `database.php` with database credentials), leading to high-impact information disclosure and potential follow-on compromise. Version 4.0.16 fixes the issue.