feat: v1 API + frontend migration

frontend/src/auth/ProtectedRoute.tsx

@@ -0,0 +1,21 @@
+import { Navigate, useLocation } from 'react-router-dom';
+import { useAuth } from './AuthContext';
+
+interface ProtectedRouteProps {
+  children: React.ReactNode;
+}
+
+export function ProtectedRoute({ children }: ProtectedRouteProps) {
+  const { isAuthenticated, isCheckingAuth } = useAuth();
+  const location = useLocation();
+
+  if (isCheckingAuth) {
+    return <div className="text-content-muted">Loading...</div>;
+  }
+
+  if (!isAuthenticated) {
+    return <Navigate to="/login" state={{ from: location }} replace />;
+  }
+
+  return children;
+}