Implement 30-day database backup retention

[rjan90]

Done Criteria

• Automated database backups retain 30 days of history
• Restores from backups within that 30-day window are verified to work
• Team documentation reflects the 30-day retention policy

Why Important

Issue #68 intentionally delivers 7-day retention for GA. This follow-up tracks the post-GA (M4.5) work to extend retention to 30 days so #68 can close once its remaining GA criteria are met.

User/Customer

Dealbot operators

Notes

• Follow-up to Set up 7 day database backups #68

[BigLep]

Triage comment from 2026 FOC Board Triage (Post GA): we have not needed to deal with dealbot backups, and might have a cloud-native-postgres and different backup solution available before we need to work this. For now we'll just rely on the Supabase provided backup time window that we have.

[Kubuxu]

We should verify the current Supabase backup configuration.