curl --request POST \
  --url https://api.example.com/api/v1/campaigns/{campaign_id}/launch-preflight \
  --header 'Authorization: Bearer <token>'

{
  "can_launch": true,
  "summary": {
    "total_rows": 123,
    "launchable_rows": 123,
    "warning_count": 123
  },
  "warnings": []
}