curl --request GET \
  --url https://api.clinkbill.dev/api/subscription/invoice/{id} \
  --header 'X-API-KEY: <api-key>' \
  --header 'X-Timestamp: <api-key>'

{
  "code": 200,
  "msg": "success",
  "data": {
    "invoiceId": "<string>",
    "subscriptionId": "<string>",
    "orderId": "<string>",
    "customerId": "<string>",
    "merchantId": "<string>",
    "status": "open",
    "createTime": 1754819712625,
    "currentPeriodStart": 1754819706689,
    "currentPeriodEnd": 1755078906689,
    "originalAmount": 9.99,
    "originalCurrency": "USD",
    "billing": "charge_automatically",
    "items": [
      {
        "invoiceItemId": "<string>",
        "amount": 9.99,
        "currency": "USD",
        "description": "<string>",
        "periodStart": 1754819706689,
        "periodEnd": 1755078906689,
        "proration": true,
        "price": {
          "productId": "<string>",
          "productName": "<string>",
          "priceId": "<string>",
          "priceSnapshotId": "<string>",
          "unitAmount": 9.99,
          "quantity": 1,
          "recurring": {
            "interval": "week",
            "trialPeriodDays": 123,
            "pricingModel": "flat_rate",
            "tiersMode": "volume"
          }
        }
      }
    ]
  }
}