- Add backend/internal/s3/ with build-tag pattern (dev vs prod) - Dev: Uses local Rustfs container (S3-compatible) - Prod: Stub for R2 Cloudflare (add AWS SDK to implement) - Add S3 env vars to .env.example and .env - Add Rustfs service to compose.yml - Add Rustfs reset to local-dev-2.sh (wipes data on each run)