Send AI Captain message

curl --request POST \
  --url https://api.smartlyq.com/v1/captain/messages \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "message": "<string>",
  "conversation_id": "<string>"
}
'

{
  "success": true,
  "data": {
    "message": {
      "id": "<string>",
      "content": "<string>",
      "created_at": "2023-11-07T05:31:56Z"
    },
    "conversation_id": "<string>"
  },
  "usage": {
    "units": 123,
    "cost": "0.0150",
    "balance_remaining": "99.9850"
  },
  "meta": {
    "request_id": "<string>",
    "timestamp": "2023-11-07T05:31:56Z"
  }
}