curl -X POST "http://localhost:5001/channel/subscriber_add" \
  -H "Content-Type: application/json" \
  -d '{
    "channel_id": "group123",
    "channel_type": 2,
    "subscribers": ["user4", "user5", "user6"],
    "reset": 0,
    "temp_subscriber": 0
  }'

{
  "status": "ok"
}