curl --request GET \
  --url https://api.goyappr.com/billing \
  --header 'Authorization: Bearer <token>'

{
  "has_payment_method": true,
  "billing_email": "jsmith@example.com",
  "balance_cents": 123,
  "balance": 123,
  "currency": "usd",
  "is_suspended": true,
  "auto_topup_enabled": true,
  "auto_topup_amount_cents": 123,
  "low_balance_threshold_cents": 123
}