curl --request POST \
  --url https://api.example.com/api/v1/staking/orders \
  --header 'Content-Type: application/json' \
  --data '
{
  "buildId": "build_20260511_0001",
  "productId": "base_usdc_nexfi_vault",
  "orderType": "subscribe",
  "walletAddress": "0xabc1230000000000000000000000000000000000",
  "amount": "1000",
  "txHash": "0x123"
}
'

{
  "code": 0,
  "msg": "ok",
  "data": {
    "orderId": "stk_20260511_0001",
    "status": "pending_chain"
  }
}