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/hooks/useAuth.ts

@@ -0,0 +1,75 @@
+import { useState, useCallback, useMemo } from 'react';
+import { startRegistration, startAuthentication } from '@simplewebauthn/browser';
+import {
+  registerBegin,
+  registerComplete,
+  loginBegin,
+  loginComplete,
+} from '../api/auth';
+
+export interface UseAuthReturn {
+  isAuthenticated: boolean;
+  login: (username: string) => Promise<void>;
+  register: (username: string) => Promise<void>;
+  logout: () => void;
+  error: string | null;
+  loading: boolean;
+}
+
+export function useAuth(): UseAuthReturn {
+  const [error, setError] = useState<string | null>(null);
+  const [loading, setLoading] = useState(false);
+  const [token, setToken] = useState<string | null>(() =>
+    localStorage.getItem('access_token')
+  );
+
+  const isAuthenticated = useMemo(() => !!token, [token]);
+
+  const register = useCallback(async (username: string) => {
+    setLoading(true);
+    setError(null);
+    try {
+      const { options } = await registerBegin(username);
+      const attestation = await startRegistration({ optionsJSON: options as any });
+      const tokens = await registerComplete(username, attestation);
+      localStorage.setItem('access_token', tokens.access_token);
+      localStorage.setItem('refresh_token', tokens.refresh_token);
+      setToken(tokens.access_token);
+    } catch (err: any) {
+      const message =
+        err?.response?.data?.detail || err?.message || 'Registration failed';
+      setError(message);
+      throw err;
+    } finally {
+      setLoading(false);
+    }
+  }, []);
+
+  const login = useCallback(async (username: string) => {
+    setLoading(true);
+    setError(null);
+    try {
+      const { options } = await loginBegin(username);
+      const assertion = await startAuthentication({ optionsJSON: options as any });
+      const tokens = await loginComplete(username, assertion);
+      localStorage.setItem('access_token', tokens.access_token);
+      localStorage.setItem('refresh_token', tokens.refresh_token);
+      setToken(tokens.access_token);
+    } catch (err: any) {
+      const message =
+        err?.response?.data?.detail || err?.message || 'Login failed';
+      setError(message);
+      throw err;
+    } finally {
+      setLoading(false);
+    }
+  }, []);
+
+  const logout = useCallback(() => {
+    localStorage.removeItem('access_token');
+    localStorage.removeItem('refresh_token');
+    setToken(null);
+  }, []);
+
+  return { isAuthenticated, login, register, logout, error, loading };
+}