Hangfire Recurring Jobs Transactional Email with Rovela (2026): RecurringJob.AddOrUpdate + Idempotency-Key per Window
Wire Hangfire RecurringJob.AddOrUpdate (cron / Cron.* + RecurringJobOptions) to Rovela POST /emails with server-only sending_access and a window-scoped Idempotency-Key for digests and ops reports.