Approve quote and create hosted checkout

Call only after the sender explicitly approves the exact final proof or item, recipient, total and terms. A verified sender email matching the connected owner is required. This REST endpoint normally records approval and creates/reuses the order. When the quote contains addressWarnings it instead returns a ReviewLink without an order or payment: the sender must accept the exact address risk on that scoped browser page. Caller-supplied risk flags never bypass this review. Agents should normally use MCP postedly_checkout instead: it returns a private browser review link where the user verifies their own receipt email and approves without changing the connected creator or the quoted postal sender. On an ambiguous result, read existing orders before deciding what to do; never blindly replay checkout or create a replacement quote/order.