GHSA-6x2m-p4xp-wg22: Network-AI: EnvironmentManager.backup() follows symlinked directories and copies files outside the environment root into backups

Network-AI versions up to 5.12.1 have a vulnerability in the `EnvironmentManager.backup()` function where it follows symlinks (shortcuts to other directories) when collecting files to back up. An attacker who can create a symlink in the environment data directory can trick the backup process into copying files from outside the intended environment root directory, potentially exposing sensitive information in backup artifacts.