curl --request GET \
  --url http://localhost:8080/contests/referral/{contest_id}/detailed-stats

{
  "total_participants": 123,
  "total_invited": 123,
  "total_paid_amount": 123,
  "total_unpaid": 123,
  "participants": [
    {
      "referrer_id": 123,
      "full_name": "<string>",
      "total_referrals": 123,
      "paid_referrals": 123,
      "unpaid_referrals": 123,
      "total_paid_amount": 123
    }
  ]
}