Delete keep-in-touch cadences in bulk (v2)

Delete the Team cadence (owners, admins, standard members) or the caller's own My cadence (kind) of up to 1000 contacts (contact_ids). Another member's My cadence is never touched; a contact with no cadence of that kind the caller can see is reported in not_found_contact_ids. The contacts are written in pages that commit independently, so a failed request may have deleted some: retrying the same body is safe. Closed to API keys. Workspace-only: send the X-Dex-Workspace header (400 workspace_context_required without it). Requires an Idempotency-Key header. Returns { data: { affected, ids: [cadenceId], contact_ids, not_found_contact_ids } }.