MessageSendingDetailsDto

{
    "stage": "queued",
    "attachments_total": 3,
    "attachments_ready": 2,
    "attachments_failed": 1,
    "current_attachment_id": "550e8400-e29b-41d4-a716-446655440000",
    "platform_request_id": "rq_01HXYZ..."
}