feat: autopass-based cross-device sync for Holesail Browser

- Native host: add autopass + corestore deps, sync-manager (createInvite, pairWithInvite, push/pull)
- Apply synced state via same flow as backup restore (state.json only, no certs)
- Holesail-manager: setOnStateSaved hook for sync push
- Extension: Sync dashboard page, getSyncStatus/createSyncInvite/pairWithInvite, syncApplied event
- Docs: NATIVE-HOST.md sync commands, SYNC.md

extension/dashboard/core/navigation.js

@@ -13,6 +13,7 @@ const PAGE_TITLES = {
   ssh: 'SSH Connections',
   rdp: 'Remote Desktop',
   backups: 'Backups',
+  sync: 'Sync',
   logs: 'Logs',
   settings: 'Settings'
 };