Creates a new order (products + amounts + customer data).

Minimum required fields:

• currency
• line_items
• customer_info

About customer_info:

• You can reference an existing customer using customer_info.customer_id, or
• You can provide customer details at minimum customer_info.name and customer_info.email to create the order with customer context.

How to create the order:

• Create an order only (no payment): send only the order data.
• Create an order and create the first payment charge: include charges.
• Create an order with a checkout configuration (for a hosted payment flow): include checkout.

Important rules:

• You cannot send charges and checkout in the same request (they are mutually exclusive).
• If you send shipping_contact_id and/or fiscal_entity_id, you must also send customer_info.customer_id so the API can validate those IDs against that customer.