/**
 * Service worker registration for offline product browsing.
 * localhost-only gate: in dev the SW caches HTML + module responses and
 * serves stale graphs after files are deleted/renamed.
 */
if ('serviceWorker' in navigator && !['localhost', '127.0.0.1'].includes(location.hostname)) {
  window.addEventListener('load', () => {
    navigator.serviceWorker.register('/sw.js').catch(() => {});
  });
}