Add borg-backup service with restore script

New service: borg-backup (backup group)
- Installs borgbackup from apt
- Same coverage as Kopia backup: full ~/docker/<service>/ snapshots
- Minecraft: flush world (save-all), archive, no downtime
- All others: stop → archive → restart
- Multi-destination support with per-service routing
- SSH remote repos supported natively (user@host:/path)
- Per-service pruning: keep-daily/weekly/monthly
- repo compact after each run
- Systemd timer (with cron fallback)
- repokey-blake2 encryption; key export reminder in summary
- worker.sh: run / list / info subcommands

New restore helper: extras/restore_borg_backup.sh
- Installed to ~/docker/borg-backup/restore/<dest>/
- Interactive: lists services → pick archive → inspect (/tmp) or restore in-place
- In-place restore: stops container, moves current data aside, extracts, restarts
- Old data kept as .pre-restore-DATE with rollback instructions printed

https://claude.ai/code/session_019XgsQ13XKm4Zj3cNsDNwHj

README.md

@@ -72,7 +72,7 @@ Update them any time with `sudo ./setup.sh configure`.
 | `cameras` | `frigate`, `frigate-audio`, `frigate-notify`, `sky-cam` |
 | `gaming` | `js99er`, `minecraft`, `wolf`, `wolf-pair` |
 | `extras` | `silent-send`, `sync-cc` |
-| `backup` | `backup` — complete recovery: entire `~/docker/<service>/` for every service (Minecraft: flush+snap, no downtime; others: stop/snap/start for DB consistency); `gaming-backup` — frequent game-save snapshots (Minecraft world data, emulator saves, Steam — no downtime, run hourly) |
+| `backup` | `backup` — complete recovery: entire `~/docker/<service>/` for every service via Kopia (Minecraft: flush+snap, no downtime; others: stop/snap/start for DB consistency); `borg-backup` — same coverage via Borg (chunk dedup, SSH remote repos, Borgmatic/Vorta compatible); `gaming-backup` — frequent game-save snapshots (Minecraft world data, emulator saves, Steam — no downtime, run hourly) |
 
 Run `./setup.sh --list` to see descriptions.