curl --request POST \
  --url https://api.agentixx.io/api/broadcasts/estimate \
  --header 'Content-Type: application/json' \
  --header 'x-tenant-id: <api-key>' \
  --cookie better-auth.session_token= \
  --data '
{
  "groupId": "550e8400-e29b-41d4-a716-446655440000"
}
'

{
  "count": 123
}