curl --request POST \
  --url https://api.headlesscommerce.io/v1/admin/orders/{id}/fulfillments \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "lines": [
    {
      "order_line_id": "<string>",
      "quantity": 2
    }
  ],
  "tracking_number": "<string>",
  "tracking_url": "<string>",
  "carrier": "<string>"
}
'

{
  "id": "<string>",
  "order_id": "<string>",
  "status": "pending",
  "tracking_number": "<string>",
  "tracking_url": "<string>",
  "carrier": "<string>",
  "lines": [
    {
      "order_line_id": "<string>",
      "quantity": 123
    }
  ],
  "created_at": "2023-11-07T05:31:56Z",
  "shipped_at": "2023-11-07T05:31:56Z",
  "delivered_at": "2023-11-07T05:31:56Z"
}