fix(security): resolve FLAW-08 with token_version invalidation and jwt blacklist

frontend/src/App.tsx

@@ -567,7 +567,11 @@ export const App: React.FC = () => {
   const handleLogout = async () => {
     triggerHaptic(20);
     disconnectWebSocket();
-    clearToken();
+    try {
+      await api.logout();
+    } catch {
+      clearToken();
+    }
     setUser(null);
     setShowProfileMenu(false);
     setActiveTab('triage');