curl --request POST \
  --url https://app.tuco.ai/api/campaigns/{id}/leads \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "leadId": "69b2c41d352a78479d2c623b"
}
'

{
  "success": true,
  "leadId": "69b2c41d352a78479d2c623b",
  "campaignId": "69ab444ac1feb77d7f46462f",
  "messageCount": 0,
  "message": "Lead already in campaign (re-entry not allowed).",
  "alreadyInCampaign": true,
  "existingLeadIds": [
    "69b2c41d352a78479d2c623b"
  ],
  "ghlContactId": "aMUQn0u0Z7cw0NQ7tJ5R",
  "ghlLocationId": "eL7DD22BdZ0rismu7qCA"
}