mgr/dashboard: Sanitize toast HTML and optimize notification service
- Escape user-controlled content before Carbon innerHTML rendering
- Whitelist localStorage deserialization keys, prune stale read map
- Replace deep equality with ID comparison in removeToast
- Gate ngAfterViewChecked DOM queries behind a dirty flag
- Deduplicate by title+type+message; show occurrences count
- Fix bell icon unread dot clearing on new occurrences
- Fix view more pre-selection via route queryParams observable
- Save individual notifications instead of HTML-merged messages
- Convert notifications bell component to signals with OnPush
- Add OnPush to notification-item and toast components
- Add e2e tests
- Fix styling of notification panel