fix(db): prevent refresh shutdown hang

[caiopizzol]

Monthly refreshes can outlive Postgres.js’s default connection lifetime, leaving shutdown waiting forever after publication and backup succeed. This keeps completed workers resident on Moor.

• Treats the database connection as batch-scoped so long-held advisory locks remain valid.
• Bounds final cleanup to prevent another indefinite worker leak.

[cubic-dev-ai]

No issues found across 1 file

_{Re-trigger cubic}