[Feature] General file backup in a separate section of the mobile app

I have searched the existing feature requests, both open and closed, to make sure this is not a duplicate request. • Yes The feature Immich is an excellent solution for backing up and browsing photos and videos. However, smartphones also contain important files that cannot be backed up using Immich's existing media backup functionality. For example, messaging apps (WhatsApp, Signal, etc.) may create local encrypted backup files. Other apps may store documents, PDFs, exports, archives, or other files that users want to keep safe on their own server. I would like to see a general file backup feature in the Immich mobile app, alongside the existing photo and video functionality. Ideally, the app would provide two separate sections: • Photos & Videos: The existing media library and backup functionality. • Files: A separate area for backing up arbitrary files and folders, including files that Immich cannot display as media. Users should be able…