Create or fully replace an order and its payments and line items. The request body is the complete order: any payments or line items left out are removed. Returns 200 for both create and update, with the saved order and a warnings array for any references that could not be resolved. The first order sent for a location sets that location's cutover date from its order_date, and the cutover date cannot be changed afterwards. Orders dated before the cutover date are not readable, so send historical orders oldest first.