feat(telemetry): track API credit top-up success via audit events (#6500)

Summary
- Add TelemetryEvents.API_CREDIT_TOPUP_SUCCEEDED and provider method
trackApiCreditTopupSucceeded
- Introduce topupTrackerStore to persist pending top-ups per user
(localStorage) and reconcile against recent audit logs
- Hook purchase flow to start tracking before opening Stripe checkout
- Reconcile after fetching audit events (UsageLogsTable) and after
fetchBalance, then emit telemetry, refresh balance, and clear pending
- Minor refactor in customerEventsService to return awaited result

Implementation details
- Matching strategy:
  - Event type: credit_added
  - Time window: createdAt between top-up start time and +24h
  - Amount: if known, e.params.amount must equal expected cents
- Cross-tab/user changes: synchronize via storage event and userId
watcher

Limitations / Follow-up
- Reconciliation fetches only page 1 (limit 10) of events; in
high-volume cases, a recent credit_added could fall outside the first
page
- The window and pagination issue will be "resolved by a followup PR to
core and cloud"

Files touched
- src/stores/topupTrackerStore.ts (new)
- src/components/dialog/content/setting/UsageLogsTable.vue
- src/composables/auth/useFirebaseAuthActions.ts
- src/platform/telemetry/providers/cloud/MixpanelTelemetryProvider.ts
- src/platform/telemetry/types.ts
- src/services/customerEventsService.ts

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-6500-feat-telemetry-track-API-credit-top-up-success-via-audit-events-29e6d73d365081169941efae70cf71fe)
by [Unito](https://www.unito.io)

---------

Co-authored-by: Christian Byrne <chrbyrne96@gmail.com>
Co-authored-by: Claude <noreply@anthropic.com>

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

@@ -1,6 +1,11 @@
 import type { OverridedMixpanel } from 'mixpanel-browser'
 
 import { useCurrentUser } from '@/composables/auth/useCurrentUser'
+import {
+  checkForCompletedTopup as checkTopupUtil,
+  clearTopupTracking as clearTopupUtil,
+  startTopupTracking as startTopupUtil
+} from '@/platform/telemetry/topupTracker'
 import { useWorkflowStore } from '@/platform/workflow/management/stores/workflowStore'
 import { useWorkflowTemplatesStore } from '@/platform/workflow/templates/repositories/workflowTemplatesStore'
 import { app } from '@/scripts/app'
@@ -172,6 +177,23 @@ export class MixpanelTelemetryProvider implements TelemetryProvider {
     )
   }
 
+  trackApiCreditTopupSucceeded(): void {
+    this.trackEvent(TelemetryEvents.API_CREDIT_TOPUP_SUCCEEDED)
+  }
+
+  // Credit top-up tracking methods (composition with utility functions)
+  startTopupTracking(): void {
+    startTopupUtil()
+  }
+
+  checkForCompletedTopup(events: any[] | undefined | null): boolean {
+    return checkTopupUtil(events)
+  }
+
+  clearTopupTracking(): void {
+    clearTopupUtil()
+  }
+
   trackRunButton(options?: { subscribe_to_run?: boolean }): void {
     const executionContext = this.getExecutionContext()