[Partner] New vendorSkuId field on Get Subscription By ID

The Get Subscription By ID endpoint (GET /v1/subscriptions/{subscriptionId}) now returns a new vendorSkuId field for Microsoft subscriptions. This GUID is Microsoft's SKU-level identifier and matches the skuId returned by Microsoft Graph's /subscribedSkus endpoint, giving you a reliable bridge between your Pax8 subscriptions and the provisioned licenses in the customer's Microsoft tenant.

Use vendorSkuId to reconcile used vs. unused seats: fetch the subscription from Pax8, match its vendorSkuId to a skuId in Graph /subscribedSkus, and compare consumedUnits against prepaidUnits.enabled. If no unused seats remain, order more through Pax8.

Note that Microsoft Graph aggregates seats per SKU rather than per commerce subscription, so multiple Pax8 subscriptions for the same product share one vendorSkuId. The field is returned on the subscription detail endpoint only, not on List Subscriptions. See the Mapping Pax8 Identifiers to Microsoft Graph API guide at https://devx.pax8.com/docs/microsoft-subscription-reconciliation for the full workflow.