AI Assistant: frontend - chat app, sidebar, settings with 4 tabs

frontend/src/components/layout/TopBar.tsx

@@ -14,7 +14,7 @@ export function TopBar() {
   const { t } = useTranslation();
   const navigate = useNavigate();
   const { user } = useAuthStore();
-  const { toggleSidebar } = useUIStore();
+  const { toggleSidebar, toggleAISidebar } = useUIStore();
   const { currentTenant, availableTenants, switchTenant, isSwitching } = useTenant();
   const logoutMutation = useLogout();
 
@@ -69,6 +69,18 @@ export function TopBar() {
           </svg>
         </button>
 
+        {/* AI Assistant toggle */}
+        <button
+          onClick={toggleAISidebar}
+          className="p-2 rounded-md hover:bg-secondary-100 min-h-touch min-w-touch flex items-center justify-center focus:outline-none focus-visible:ring-2 focus-visible:ring-primary-500"
+          aria-label="KI Assistent"
+          title="KI Assistent"
+        >
+          <svg className="w-5 h-5" fill="none" viewBox="0 0 24 24" stroke="currentColor" aria-hidden="true">
+            <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M9.75 17L9 20l-1 1h8l-1-1-.75-3M3 13h18M5 17h14a2 2 0 002-2V5a2 2 0 00-2-2H5a2 2 0 00-2 2v10a2 2 0 002 2z" />
+          </svg>
+        </button>
+
         {/* Tenant switcher */}
         <div ref={tenantRef} className="relative">
           <button