Public storefront endpoint. Create an order from direct items, from the guest cart referenced by X-Scalev-Guest-Token, or from direct items while clearing the referenced guest cart after successful order creation. Direct checkout items are store-scoped and not blocked by storefront listing visibility. Product prices, discounts, shipping, Other Income, the Store customer-fee policy, and service fees are recalculated from current backend data during creation. Preview values are not confirmation inputs and do not produce a quote-conflict response.