curl --request POST \
  --url https://astrasend-mocha.vercel.app/api/public/lists/{id}/contacts \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "contacts": [
    {
      "phone": "+15551234567",
      "first_name": "<string>",
      "last_name": "<string>",
      "source": "<string>"
    }
  ]
}
'

{
  "ok": true
}