Webhooks
- /api/v1/webhooks registers https endpoints for order, shipment, invoice, credit memo, payment and return events, with a signing secret shown once, a test event per type, delivery logs and secret rotation. Needs a key with the webhooks:manage scope.
- Deliveries carry Balaji-Signature: t=<unix seconds>,v1=<HMAC-SHA256 hex>. Sending stays off until Balaji turns it on. New code: WEBHOOKS_UNAVAILABLE.