CVE-2026-45620: AVideo CVE-2026-43881 incomplete fix - `objects/mention.json.php:17` is an unauthenticated user enumeration sibling that survives `d9cdc7024`

CVE-2026-43881 fix d9cdc7024 patched users.json.php only. The same anti-pattern survives at master HEAD in:

objects/mention.json.php:17     $ignoreAdmin = true;
objects/mention.json.php:18     $users = User::getAllUsers($ignoreAdmin,
['name', 'email', 'user', 'channelName'], 'a');

No User::loginCheck(), no admin gate. Only entry guard: preg_match('/^@/', $_REQUEST['term']) and hard-coded rowCount=10.