Backend:
- Add IsEncryptionEnabled() method to ConfigPersistence
- Include encryption status in /api/notifications/health response
- Allows frontend to warn when credentials are stored in plaintext
Frontend:
- Update NotificationHealth type to include encryption.enabled field
- Frontend can now display warnings when encryption is disabled
This addresses the P2 requirement for encryption visibility, allowing
operators to know when notification credentials are not encrypted at rest.
Critical fixes (P0):
- Fix cooldown timing: Mark cooldown only after successful delivery, not before enqueue
- Add os.MkdirAll to queue initialization to prevent silent failures on fresh installs
- Add DNS re-validation at webhook send time to prevent DNS rebinding SSRF attacks
- Add SSRF validation for Apprise HTTP URLs
- Remove secret logging (bot tokens, routing keys) from debug logs
- Implement lastNotified cleanup to prevent unbounded memory growth
- Use shared HTTP client for webhooks to enable TLS connection reuse
- Add fallback to direct sending when queue enqueue fails
- Make queue worker concurrent (5 workers with semaphore) to prevent head-of-line blocking
- Fix webhook rate limiter race condition with separate mutex
- Fix email manager thread safety with mutex on rate limiter
- Fix grouping timer leak by adding stopCleanup signal
- Fix webhook 429 double sleep (use Retry-After OR backoff, not both)
Frontend improvements:
- Add queue/DLQ management API methods (getQueueStats, getDLQ, retryDLQItem, deleteDLQItem)
- Add getNotificationHealth and getWebhookHistory endpoints
- Add Apprise test support to NotificationTestRequest type
Related to notification system audit
