풀필먼트 지갑 잔액 API

{
  "balance": {
    "available": {
      "amount": 500000,
      "currency": "CNY"
    },
    "frozen": {
      "amount": 12000,
      "currency": "CNY"
    },
    "total": {
      "amount": 512000,
      "currency": "CNY"
    }
  },
  "request_id": "req_..."
}