curl --request POST \
  --url https://swap-api.flux.fun/v1/order/calldata \
  --header 'Content-Type: application/json' \
  --header 'x-api-key: <api-key>' \
  --data '
{
  "orderType": "MarketOrder",
  "order": {
    "quoteToken": {
      "type": "kalshi",
      "data": {
        "marketId": "KXBTC-24NOV30-T65000",
        "side": "yes"
      }
    },
    "baseToken": {
      "type": "kalshi",
      "data": {
        "marketId": "KXBTC-24NOV30-T65000",
        "side": "yes"
      }
    },
    "orderType": "BUY",
    "baseQuantity": "100",
    "minQuoteQuantityOut": "95",
    "maxQuoteQuantityIn": "105"
  },
  "chainId": 8453,
  "clientId": "order-123",
  "includeTokenTransfer": false,
  "userAddress": "0x...",
  "receiverAddress": "0x..."
}
'

{
  "success": true,
  "transactions": [
    {
      "to": "0x1234567890abcdef1234567890abcdef12345678",
      "value": "0",
      "data": "0x1234567890abcdef..."
    }
  ],
  "description": "Submit order for BTC-100K market"
}