CVE-2026-55579: Pheditor: Hardcoded default password 'admin' with no forced change enables full application compromise

Pheditor ships with a hardcoded default password admin (SHA-512 hash stored at pheditor.php:11). There is no mechanism to force a password change on first login. Any deployment using the default credentials grants an attacker full access to the file editor, file upload, and terminal features, enabling arbitrary file read/write and remote code execution.