Updates an existing seller, addressed by its server-assigned uuid. Functionally equivalent to calling POST /api/v1/sellers with the same external_reference_id (which is the recommended path); this endpoint exists for cases where the integration prefers UUID-addressed updates.

The body cannot change external_reference_id — that field is the upsert key and is set on creation only. To rename a seller externally, register a new one and migrate orders to it.