Quarterly backup restore drill

[thefiredev-cloud]

Context

DR plan landed in 0b365c6 (PR #48). Execute first quarterly backup restore drill to verify backups are usable.

Acceptance criteria

• Supabase PITR tested on staging clone (restore to T-1h)
• Netlify env var backup verified
• Asset bucket snapshot restored
• RPO/RTO measured and compared against SLO
• Results documented in runbook

Blocker

None.

Related planning docs

• docs/plans/backup-dr.md