Prod DB dumps and Forgejo (db + data volume) are now copied off-box to the
era5-thermograph S3 bucket, age-encrypted to the vault recipient so the host
age key at /etc/thermograph/age.key decrypts them for restore. Nothing plaintext
leaves the box; no local intermediate (streamed via age | rclone rcat).
ops-cron: the prod pg_dump job gains an off-box push; a new forgejo-backup job
dumps Forgejo's Postgres + tars its data volume on beta (the git host had NO
backup at all). 30-day off-box retention on both. S3 creds are Forgejo Actions
secrets (S3_ENDPOINT/BUCKET/ACCESS_KEY/SECRET_KEY), mirrored into the SOPS vault
(prod.yaml/beta.yaml) for host-side use. Contabo needs path-style addressing.
Adds deploy/backup/README.md with the DR restore runbook.
