Retrieves a single webhook endpoint's configuration and delivery stats by its ID.

The response includes url, description, events, status, enabled, delivery stats (success/failure counts, last delivery timestamps), auto-disable state, and secret_prefix — the full signing secret is only ever returned when the endpoint is created, not here. Visibility is scoped to the caller: customer-authenticated requests see company-owned webhooks (shared across the company's users/tokens), while partner/integration callers see only the webhooks they own; an endpoint outside the caller's scope returns 404 the same as a nonexistent one.