curl --request GET \
  --url https://api.example.com/api/billing/invoices/{id} \
  --cookie better-auth.session_token=

{
  "id": "<string>",
  "ownerType": "user",
  "ownerId": "<string>",
  "periodYear": 123,
  "periodMonth": 123,
  "periodStart": "<string>",
  "periodEnd": "<string>",
  "currency": "<string>",
  "lineItems": [
    {
      "resourceType": "<string>",
      "resourceId": "<string>",
      "billingType": "hourly",
      "quantity": 123,
      "ratePerUnit": 123,
      "amount": 123,
      "resourceLabel": "<string>"
    }
  ],
  "subtotal": 123,
  "tax": 123,
  "total": 123,
  "status": "draft",
  "createdAt": "<string>",
  "updatedAt": "<string>",
  "issuedAt": "<string>",
  "voidedAt": "<string>",
  "notes": "<string>"
}