Add Litestream SQLite backup to R2

[swalkinshaw]

Continuously replicate the SQLite database to R2 via Litestream for production resilience and fast local dev setup. In production, Litestream wraps wpcomposer serve as a sidecar, streaming WAL changes to R2.

• Add db restore CLI command to pull production snapshots locally
• Add Ansible tasks to install Litestream and deploy its config
• Wrap systemd ExecStart with litestream replicate -exec
• Add make db-restore target
• Add LitestreamConfig to app config (LITESTREAM_BUCKET, LITESTREAM_PATH)

Before mergin

• setup separate R2 bucket for backups

Cost Estimate

• R2 pricing: $0.015/GB/month storage, free egress, Class A ops $4.50/million, Class B $0.36/million.
• Storage: Litestream keeps snapshots (default: every 24h) + WAL segments. With a ~162MB DB and daily snapshots with retention, expect ~500MB–1GB total.
• Cost: ~$0.01–0.02/month
• Operations: WAL segments upload continuously on writes. Pipeline runs every 5 min + HTTP telemetry writes. Estimate ~5,000–10,000 PUT operations/day.
• Cost: ~$0.70/month
• Restores: Free egress from R2, minimal Class B reads. Cost: effectively $0

Total estimate: ~$1/month or less