feat: desktop startup auto-update before main app launch

Check server version on launch, download/install/relaunch if newer,
then show the main UI. Manual update check no longer triggers full install.

Co-authored-by: Cursor <cursoragent@cursor.com>

desktop/src/main.tsx

@@ -4,17 +4,11 @@ import ReactDOM from 'react-dom/client';
 import { initStorage, refreshApiBaseFromStorage } from '@goldenchart/shared';
 import { installDesktopBridge } from './bridge/installDesktopBridge';
 import { ensureDesktopApiBase } from './ensureDesktopApiBase';
+import { StartupUpdateGate } from './StartupUpdateGate';
 import App from '@frontend/App';
 
 installDesktopBridge();
 
-/** 시작 시 백그라운드 업데이트 확인 (실패 무시) */
-void import('./bridge/updater').then(({ checkForUpdates }) => {
-  window.setTimeout(() => {
-    void checkForUpdates().catch(() => { /* offline 등 */ });
-  }, 8000);
-});
-
 async function bootstrap() {
   await initStorage();
   ensureDesktopApiBase();
@@ -22,7 +16,9 @@ async function bootstrap() {
 
   ReactDOM.createRoot(document.getElementById('root')!).render(
     <React.StrictMode>
-      <App />
+      <StartupUpdateGate>
+        <App />
+      </StartupUpdateGate>
     </React.StrictMode>,
   );
 }