DialogFirstMessageDto

{
    "content": "Здравствуйте! Подскажите по возврату товара.",
    "timestamp": "2025-12-25T10:00:00Z",
    "sender": {
        "id": "550e8400-e29b-41d4-a716-446655440000",
        "type": "lead",
        "external_id": "123456789",
        "profile": {
            "first_name": "Иван",
            "last_name": "Петров",
            "username": "ivan_petrov",
            "avatar_url": "https://example.com/avatar.jpg",
            "platform_type": "vk",
            "operator_notes": "Просил связаться после 18:00",
            "space_kind": "discord_guild",
            "space_type": "community",
            "source_url": "https://t.me/example"
        }
    },
    "lead_id": "507f1f77bcf86cd799439011",
    "action_type": "message_created",
    "attachments": [
        {
            "type": "photo",
            "count": 2
        },
        {
            "type": "document",
            "count": 1
        }
    ]
}