[web] update webhook event handlers for Stripe custom checkout (#28526)

* do not emit subscription-started when status is incomplete
* emit subscription-started when incomplete subscription transitions to active
* do not emit subscription-expired when status is incomplete_expired
* do not sync incomplete or incomplete_expired Stripe subscriptions
* allow `incomplete*` status to better guard against syncing

GitOrigin-RevId: 4e851f654dcb4bf356280197dd158e834175df12

services/web/types/subscription/dashboard/subscription.ts

@@ -14,6 +14,8 @@ export type SubscriptionState =
   | 'expired'
   | 'paused'
   | 'past_due'
+  | 'incomplete'
+  | 'incomplete_expired'
 
 // when puchasing a new add-on in recurly, we only need to provide the code
 export type PurchasingAddOnCode = {