Add a litestream service (0.5.17) to the compose stack that streams
/data/mealquest.db over SFTP to the Synology NAS with a dedicated key,
daily snapshots kept for a week. Add a systemd timer that rsyncs the
media directory to the NAS nightly at 03:30.
Task: d2f2e87e-5114-4ef1-93ab-360ffb5c009e
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
