Fix: Stream in gleichem Fenster öffnen + Update-Dialog Abbrechen-Button

- Stream-Tile Klick öffnet Join-Modal statt neues Fenster
- checkForUpdates optional chaining für alte Electron App
- Abbrechen-Button im Update-Check Dialog
- 15s Timeout falls Electron nicht antwortet

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

web/src/App.tsx

@@ -106,7 +106,11 @@ export default function App() {
 
   const handleCheckForUpdates = () => {
     setUpdateState('checking');
-    (window as any).electronAPI?.checkForUpdates();
+    (window as any).electronAPI?.checkForUpdates?.();
+    // Timeout: falls Electron nicht antwortet, nach 15s zurücksetzen
+    setTimeout(() => {
+      setUpdateState(prev => prev === 'checking' ? 'error' : prev);
+    }, 15000);
   };
 
   // Tab icon mapping
@@ -181,6 +185,9 @@ export default function App() {
                 <div className="hub-update-progress">
                   <div className="hub-update-progress-bar" />
                 </div>
+                <button className="hub-update-btn" onClick={() => setUpdateState('idle')}>
+                  Abbrechen
+                </button>
               </>
             )}
             {updateState === 'downloading' && (

web/src/plugins/streaming/StreamingTab.tsx

@@ -611,7 +611,7 @@ export default function StreamingTab({ data }: { data: any }) {
           {streams
             .filter(s => s.id !== myStreamId)
             .map(s => (
-              <div key={s.id} className="stream-tile" onClick={() => openInNewWindow(s.id)}>
+              <div key={s.id} className="stream-tile" onClick={() => openJoinModal(s)}>
                 <div className="stream-tile-preview">
                   <span className="stream-tile-icon">{'\u{1F5A5}\uFE0F'}</span>
                   <span className="stream-live-badge"><span className="stream-live-dot" /> LIVE</span>