feat: set subscription tier as PostHog user property (#9764)

Sets subscription_tier as a PostHog person property via people.set after
user identification. Watches for async subscription status resolution so
the property updates even if the API responds after identify.

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-9764-feat-set-subscription-tier-as-PostHog-user-property-3216d73d3650812f8afcee0a830e434d)
by [Unito](https://www.unito.io)

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
Co-authored-by: Christian Byrne <cbyrne@comfy.org>

src/platform/telemetry/providers/cloud/PostHogTelemetryProvider.test.ts

@@ -50,6 +50,12 @@ vi.mock('@/platform/remoteConfig/remoteConfig', () => ({
 
 vi.mock('posthog-js', () => hoisted.mockPosthog)
 
+vi.mock('@/platform/cloud/subscription/composables/useSubscription', () => ({
+  useSubscription: () => ({
+    subscriptionTier: { value: null }
+  })
+}))
+
 import { PostHogTelemetryProvider } from './PostHogTelemetryProvider'
 
 function createProvider(

src/platform/telemetry/providers/cloud/PostHogTelemetryProvider.ts

@@ -2,6 +2,7 @@ import type { PostHog } from 'posthog-js'
 import { watch } from 'vue'
 
 import { useCurrentUser } from '@/composables/auth/useCurrentUser'
+import { useSubscription } from '@/platform/cloud/subscription/composables/useSubscription'
 import { remoteConfig } from '@/platform/remoteConfig/remoteConfig'
 import type { RemoteConfig } from '@/platform/remoteConfig/types'
 
@@ -119,6 +120,7 @@ export class PostHogTelemetryProvider implements TelemetryProvider {
             useCurrentUser().onUserResolved((user) => {
               if (this.posthog && user.id) {
                 this.posthog.identify(user.id)
+                this.setSubscriptionProperties()
               }
             })
           })
@@ -211,6 +213,19 @@ export class PostHogTelemetryProvider implements TelemetryProvider {
     )
   }
 
+  private setSubscriptionProperties(): void {
+    const { subscriptionTier } = useSubscription()
+    watch(
+      subscriptionTier,
+      (tier) => {
+        if (tier && this.posthog) {
+          this.posthog.people.set({ subscription_tier: tier })
+        }
+      },
+      { immediate: true }
+    )
+  }
+
   trackSignupOpened(): void {
     this.trackEvent(TelemetryEvents.USER_SIGN_UP_OPENED)
   }