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

native-host/host/handlers/index.js

@@ -11,6 +11,7 @@ const caHandlers = require('./ca.js');
 const sshHandlers = require('./ssh.js');
 const rdpHandlers = require('./rdp.js');
 const backupHandlers = require('./backup.js');
+const syncHandlers = require('./sync.js');
 
 /**
  * Build the handler registry. Pass the same deps that message-router has.
@@ -24,7 +25,8 @@ function buildHandlers(deps) {
     ...caHandlers.register(deps),
     ...sshHandlers.register(deps),
     ...rdpHandlers.register(deps),
-    ...backupHandlers.register(deps)
+    ...backupHandlers.register(deps),
+    ...syncHandlers.register(deps)
   ];
 
   const map = new Map();