Add two new commands to npx sealgen:

• backup — dumps mongo DB, all uploaded_files and meilisearch index files to a .tar.gz file. The output filename includes the current date and time and the name of the app like myapp-2025-12-10_19-51-02.tar.gz
• restore backup.tar.gz — that takes a .tar.gz backup file and restores it

The script should be aware of the config of the current app — so if it stores uploaded_files in a non-standard directory, for example, the script should handle that. Just reading and executing config.ts should be enough.