if ('serviceWorker' in navigator && !/localhost|127.0.0.1/.test(location.hostname)) {
window.addEventListener('load', () => {
navigator.serviceWorker.register('/sw.js')
.then(() => console.log('✅ PWA: Service Worker 已注册'))
.catch((err) => console.warn('⚠️ PWA: SW 注册失败', err));
});
}