feat: add offline Sentry error queue

[OkeyAmy]

Summary

• Add a client-side Sentry wrapper that queues offline error records in IndexedDB under sentry/offlineQueue, with 500-record LRU capacity, 5-second deduplication, exponential retry backoff, uptime reset, and max-attempt dropping.
• Add an application error boundary that uses the offline-aware queue and surfaces queued report counts with a retry fallback.
• Install a connectivity bridge at the app provider root to replay queued errors when the browser comes back online.
• Route WebSocket connection failures and telemetry API 5xx responses through the offline-aware Sentry queue.

Closes #53

[JamesEjembi]

LGTM