AWS EventBridge Scheduler Transactional Email with Rovela (2026): Lambda cron + Idempotency-Key per Window
Run Amazon EventBridge Scheduler (cron/rate/at) to invoke Lambda, load ROVELA_API_KEY from env or Secrets Manager, and POST /emails with Idempotency-Key scoped to the schedule window. Distinct from Netlify Scheduled Functions, Fly Scheduled Machines, Render/Railway/Vercel cron, and GitHub Actions.