Delete a webhook endpoint

Starts sending the chosen events to `url`. The response carries the signing `secret` ONCE. The endpoint receives only conversations the key’s member can see. Subscribing to message, conversation or contact events also needs `messages:read`, `conversations:read` or `contacts:read` on the key. For WhatsApp Web connections you are responsible for send volume and the ban risk. Deliveries are at-least-once: dedupe on the event `id` (also in `Gauge-Event-Id`). Order is NOT guaranteed, not even within one conversation — use `occurredAt` and the snapshot in the payload. A non-2xx answer is retried after 30 s, 5 min, 1 h and 6 h. An endpoint failing every delivery for 3 days is switched off and its owner is told.