Set up scheduled Postgres backups to cloud storage

## Summary
Set up scheduled Postgres backups and store them in cloud storage.

## Scope
- Create a scheduled backup job for Postgres.
- Store backup archives in cloud storage.
- Investigate free or low-cost storage options, including Google Drive, and choose a practical first version.
- Include retention policy, encryption, and restore documentation.
- Alert on backup failures.

## Acceptance Criteria
- Postgres backups run on a schedule.
- Backups are uploaded to selected cloud storage.
- Backup retention is documented.
- A restore procedure is documented and tested at least once.
- Backup failure visibility exists through logs or alerting.

No repository files, tests, or entry points are named. First identify how Postgres is deployed and where scheduled jobs, cloud credentials, logging, and alerting are configured; then choose a practical storage option and define retention and encryption. Done means scheduled uploads work, a restore has been tested, retention and restore steps are documented, and failures are visible.

Written by the indexing model from the issue text.