List webhook delivery log

Recent delivery attempts for one webhook destination owned by the authenticated API key user, newest first, with opaque cursor pagination. Returns 404 (identical to an unknown id) when the endpoint is not owned by the caller, so a non-owner cannot tell an owned-but-empty log apart from someone else's endpoint. Delivery rows omit the request body and signing secret. next_attempt_at is when a pending or retry delivery is next attempted; retry_schedule_reason says whether the queue is following receiver_retry_after, transient_failure, permanent_or_auth_failure, manual_redelivery, or configuration_changed; both are null while an attempt is in flight and once the delivery is delivered or dead_letter. A delivery keeps the existing eight-attempt budget, endpoint failure budget, fairness limits, and ordinary 7380-second upper-bound schedule; see POST /api/v1/webhooks for the bounded Retry-After policy. Resend a dead_letter delivery with POST /api/v1/webhooks/{id}/deliveries/{delivery_id}/redeliver.