Add: Update-Dialog fuer Electron Auto-Updater

- main.js: IPC-Events an Renderer senden wenn Update bereit
- main.js: install-update IPC Handler (quitAndInstall)
- App.tsx: Update-Banner "Neues Update verfuegbar!" mit Restart-Button
- styles.css: Update-Bar Styling passend zum Design-System

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

web/src/App.tsx

@@ -27,6 +27,7 @@ export function registerTab(pluginName: string, component: React.FC<{ data: any
 export default function App() {
   const [connected, setConnected] = useState(false);
   const [plugins, setPlugins] = useState<PluginInfo[]>([]);
+  const [updateReady, setUpdateReady] = useState(false);
   const [activeTab, setActiveTabRaw] = useState<string>(() => localStorage.getItem('hub_activeTab') ?? '');
 
   const setActiveTab = (tab: string) => {
@@ -93,6 +94,13 @@ export default function App() {
 
   const version = (import.meta as any).env?.VITE_APP_VERSION ?? '1.5.0';
 
+  // Listen for Electron auto-update events
+  useEffect(() => {
+    const api = (window as any).electronAPI;
+    if (!api?.onUpdateReady) return;
+    api.onUpdateReady(() => setUpdateReady(true));
+  }, []);
+
   // Tab icon mapping
   const tabIcons: Record<string, string> = {
     radio: '\u{1F30D}',
@@ -145,6 +153,15 @@ export default function App() {
         </div>
       </header>
 
+      {updateReady && (
+        <div className="hub-update-bar">
+          <span>Neues Update verfügbar!</span>
+          <button onClick={() => (window as any).electronAPI?.installUpdate()}>
+            Jetzt neu starten
+          </button>
+        </div>
+      )}
+
       <main className="hub-content">
         {plugins.length === 0 ? (
           <div className="hub-empty">