feat: Günther-Agent (Netzer-Style) + Expertenblick im TipModal

- AgentChat-Widget mit SSE-Streaming, Quick-Actions, Multiple-Choice
- /api/agent/chat + /api/agent/insight Routen
- Expertenblick-Panel im TipModal (lazy load)
- Günther-Icon

frontend/src/App.tsx

@@ -4,6 +4,7 @@ import MatchesPage from './pages/MatchesPage';
 import LeaderboardPage from './pages/LeaderboardPage';
 import ProfilePage from './pages/ProfilePage';
 import AdminPage from './pages/AdminPage';
+import AgentChat from './components/AgentChat';
 import styles from './App.module.css';
 
 const IS_DEV = import.meta.env.DEV;
@@ -92,6 +93,9 @@ export default function App() {
           onRefresh={handleDevRefresh}
         />
       )}
+
+      {/* Fußball-Experte Chat-Widget – immer sichtbar */}
+      <AgentChat />
     </div>
   );
 }