scripts/send-newsletter.mjs sends newsletter/<issue>/index.html via the
Resend batch API (100/batch, paced under the 10 req/s team limit, retries
rate-limit 429s/5xx, idempotency keys so re-runs resume without dupes) to
the active subscribers of a pool fetched with the scoped send key.
Adds one-click List-Unsubscribe headers. Never logs subscriber emails.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
