Resume an auto-paused webhook endpoint

DoDomain pauses an endpoint automatically once it has had NO successful delivery for 7 days AND at least 5 dead-lettered deliveries in that span (measured from the later of its last successful delivery and its creation, or its last resume). While paused (pausedAt set), new events are still recorded as deliveries but marked skipped and never sent, and redriving any of its deliveries is refused. This call resumes it: pausedAt back to null and the 7-day clock restarted. A verb sub-path, like rotate-secret, because resuming is an action rather than a property you set. Idempotent — an endpoint that is not paused comes back unchanged. It does NOT resend the skipped deliveries: redrive them from the dashboard, each with its original delivery id. A PATCH that changes the URL resumes the endpoint too. An unknown id and another app's id both answer 404.