curl -X POST "https://server.smartlead.ai/api/v1/leads/push-to-campaign?api_key=YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "campaignId": 12345,
    "action": "copy",
    "leadList": {
      "listId": 500
    }
  }'

{
  "ok": true,
  "data": {
    "total_leads": 1250,
    "pushed": 1200,
    "duplicates": 50
  }
}

{
  "message": "Invalid API Key"
}