Bulk Create Purchase Order

Operates on Purchase Orders. In the Zuper client app this module is labeled "Purchase Order" for most companies, and "Material Order" for companies in the roofing industry — the API and data shape are identical either way. Purchase Orders and Work Orders (Service Orders) share the exact same underlying schema and endpoints; they're distinguished only by the purchase_order_type field (PURCHASE_ORDER here) and the /purchase_orders vs /service_orders route prefix. Creates multiple orders in one call. Each item in purchase_orders uses the exact same field shape as the single Create endpoint's purchase_order object (see Create Purchase Order / Create Work Order), just without the outer wrapper key.