Harden Jupyter devdata prune behavior for deleted files and copy races

Fix sync robustness, devdata activation, alias cleanup, and timing-safe auth compare

Fix gateway/telegram config bugs and stabilize WhatsApp + key rotator flows

Exclude Python/system packages from sync

Implement secret filename patterns for exclusion

Implement bug fixes for file handling and JupyterLab checks

Fix prune_remote_deleted_files guard and health probe status threshold