[Task]: pgBackRest guest execution layer for automated backups

Area

Operators

Description

Extend dbaas-backupctl's guest operation allowlist beyond probe to run pgBackRest-backed
automated backups inside the DB VM.

Includes:

• New operations: validate-repository, configure-automated, inspect, disable-automated, purge-automated.
• Root-only long-operation records under /var/lib/dbaas-ops, started as named systemd services, idempotent by operation ID.
• pgBackRest stanza configuration against the repository's automated/ sub-prefix, PostgreSQL archive_mode/archive-push wiring, stanza create/adopt, pgbackrest check, first full backup seed.
• Full/differential scheduling (weekly full, UID-derived start window, shared flock) with stopped-VM catch-up and timer coalescing.
• Retention configuration (repo1-retention-full-type=time) with pgBackRest-driven expiration, not S3 object age.
• inspect reporting real recovery-window data (last backup, current operation, oldest valid full, latest archived WAL, effective earliest/latest restorable times).

Completion condition: the verified pgBackRest lab procedure can be reproduced end-to-end through the
restricted protocol, with no arbitrary shell command path.

Related Issues

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