With --keep 0, prune ran tail -n +1 over the newest-first listing and deleted
every dump, including the one written seconds earlier, then reported success.
The check also rejects leading zeros, which the $((KEEP + 1)) arithmetic would
parse as octal (08 and 09 abort the script after the dump).
scripts/backup.sh dumps the Postgres database through the postgres compose
service (no host psql needed) into timestamped gzip files under backups/,
keeping the newest N (default 14). --with-data additionally tars the
bind-mounted data directory and fails loudly when files written by the
container are unreadable instead of shipping a partial archive. README gains
a Backups section with the restore one-liner and a cron example.
Closes#40
GRAB Racem