curl -X POST 'https://api.goatpay.com.br/v1/subaccount/add-balance' \
  -H 'X-API-Key: gp_live_SUA_CHAVE' \
  -H 'Content-Type: application/json' \
  -d '{ "id": "clx_subconta", "amount": 200, "description": "Aporte inicial" }'

{
  "success": true,
  "message": "Saldo adicionado à subconta",
  "data": {
    "mainTransactionId": "clx_tx_main",
    "subTransactionId": "clx_tx_sub",
    "amount": 200
  },
  "requestId": "req_abc123"
}