AVideo CVE-2026-43881 incomplete fix - `objects/mention.json.php:17` is an unauthenticated user enumeration

WWBN AVideo is an open source video platform. In 29.0 and earlier, objects/mention.json.php has no User::loginCheck() or admin gate. It only has an entry guard: preg_match('/^@/', $_REQUEST['term']) and hard-coded rowCount=10. This enables unauthenticated user enumeration.