Preview order details

curl --request POST \
  --url https://api.etherfuse.com/ramp/order-preview \
  --header 'Content-Type: application/json' \
  --header 'X-API-Key: <api-key>' \
  --data '{
  "amount_fiat": 100,
  "direction": "onramp"
}'

{
  "amount_fiat": 123,
  "amount_crypto": 123,
  "direction": "onramp",
  "settlement_time": "<string>"
}