Recibir mensaje del usuario final

{
  "field": "messages",
  "object": "message_event",
  "event_type": "message",
  "timestamp": 1776134352163,
  "project_id": "PROJECT_ID",
  "room_id": "ROOM_ID",
  "contact": {
    "id": "USER_ID",
    "name": "USER_NAME"
  },
  "conversation": {
    "id": "CONVERSATION_ID"
  },
  "bot": {
    "id": "BOT_ID",
    "name": "BOT_NAME"
  },
  "value": {
    "id": "MESSAGE_ID",
    "type": "image",
    "content": {
      "url": "https://storage.example.com/media/image.jpg",
      "mime_type": "image/jpeg"
    }
  }
}