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/components/dialog/content/setting/UsageLogsTable.vue

@@ -96,6 +96,7 @@ import Message from 'primevue/message'
 import ProgressSpinner from 'primevue/progressspinner'
 import { computed, ref } from 'vue'
 
+import { useTelemetry } from '@/platform/telemetry'
 import type { AuditLog } from '@/services/customerEventsService'
 import {
   EventType,
@@ -159,6 +160,9 @@ const loadEvents = async () => {
       if (response.totalPages) {
         pagination.value.totalPages = response.totalPages
       }
+
+      // Check if a pending top-up has completed
+      useTelemetry()?.checkForCompletedTopup(response.events)
     } else {
       error.value = customerEventService.error.value || 'Failed to load events'
     }