Add DragonflyDB integration for JWT revocation and implement rate limiting for authentication routes

src/contexts/AuthContext.jsx

@@ -38,7 +38,12 @@ export function AuthProvider({ children }) {
     return res.data.user;
   }, []);
 
-  const logout = useCallback(() => {
+  const logout = useCallback(async () => {
+    try {
+      await api.post('/auth/logout');
+    } catch {
+      // ignore — token is removed locally regardless
+    }
     localStorage.removeItem('token');
     setUser(null);
   }, []);