feat: dashboard setup with passkey authentication

Scaffold Vite + React + TypeScript project with Tailwind CSS dark theme.
Add Axios API client with JWT interceptor and auto-refresh, WebAuthn
passkey auth flow (register/login), protected route wrapper, and React
Router with public and protected routes.

dashboard/src/components/ProtectedRoute.tsx

@@ -0,0 +1,16 @@
+import type { ReactNode } from 'react';
+import { Navigate } from 'react-router-dom';
+
+interface ProtectedRouteProps {
+  children: ReactNode;
+}
+
+export function ProtectedRoute({ children }: ProtectedRouteProps) {
+  const token = localStorage.getItem('access_token');
+
+  if (!token) {
+    return <Navigate to="/login" replace />;
+  }
+
+  return <>{children}</>;
+}