refactor: remove KI-Agent chat widget and backend route

frontend/src/App.tsx

@@ -5,7 +5,6 @@ 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 || import.meta.env.VITE_TEST_MODE === 'true';
@@ -121,9 +120,6 @@ export default function App() {
           onRefresh={handleDevRefresh}
         />
       )}
-
-      {/* Fußball-Experte Chat-Widget – immer sichtbar */}
-      <AgentChat />
     </div>
   );
 }