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/main.tsx

@@ -0,0 +1,26 @@
+import { StrictMode } from 'react';
+import { createRoot } from 'react-dom/client';
+import { BrowserRouter } from 'react-router-dom';
+import { QueryClient, QueryClientProvider } from '@tanstack/react-query';
+import App from './App';
+import './index.css';
+
+const queryClient = new QueryClient({
+  defaultOptions: {
+    queries: {
+      staleTime: 30_000,
+      retry: 1,
+      refetchOnWindowFocus: false,
+    },
+  },
+});
+
+createRoot(document.getElementById('root')!).render(
+  <StrictMode>
+    <QueryClientProvider client={queryClient}>
+      <BrowserRouter>
+        <App />
+      </BrowserRouter>
+    </QueryClientProvider>
+  </StrictMode>
+);