Paddle Billing Webhook Email with Rovela (2026): Paddle-Signature + Idempotency-Key
Verify Paddle-Signature (HMAC-SHA256 of ts:rawBody), handle transaction.completed / subscription.created, resolve buyer email, and send branded confirmations via Rovela POST /emails with Idempotency-Key = paddle-transaction.completed-{txn_id} or paddle-subscription.created-{sub_id}. Paddle owns checkout; Rovela delivers. Distinct from Stripe, Shopify, and Lemon Squeezy webhook posts.