Backup to remote storage (S3, Google Drive, OneDrive)

[michidk]

Problem

Auto-backups currently save to the local filesystem. If the server dies or the disk fails, backups are lost along with the data they were supposed to protect.

Proposal

Allow configuring remote backup destinations in the admin panel:

• S3-compatible — covers AWS S3, Backblaze B2, MinIO, etc.
• Google Drive — OAuth-based, widely used
• OneDrive — same, common in corporate/family setups

How it could work

• Admin panel gets a "Backup Destination" setting alongside the existing schedule/retention config
• Local backup stays the default, remote is opt-in
• Could support multiple destinations (local + one remote)
• Retention policies apply to remote backups the same way

Why this is useful

• Proper 3-2-1 backup strategy — off-site copy protects against disk failure, accidental deletion, or server loss
• Self-hosters running TREK on a single machine are especially vulnerable without remote backups
• Removes the need to set up external cron jobs or rsync scripts to move backups off the server

[jubnl]

Hey, this will be available in v4. The latest prerelease already contain the external storage option, feel free to try it out!