Add ChronoSeal product website

www/js/pwa.js

@@ -0,0 +1,41 @@
+/* ============================================================
+   ChronoSeal Website — pwa.js
+   Progressive Web App: service worker registration + install
+   ============================================================ */
+
+(function () {
+  'use strict';
+
+  if ('serviceWorker' in navigator) {
+    window.addEventListener('load', function () {
+      navigator.serviceWorker.register('/sw.js').then(function (reg) {
+        /* Update found — silent refresh */
+        reg.addEventListener('updatefound', function () {
+          var worker = reg.installing;
+          if (!worker) return;
+          worker.addEventListener('statechange', function () {
+            if (worker.state === 'activated' && navigator.serviceWorker.controller) {
+              /* New version available — user can refresh */
+            }
+          });
+        });
+      }).catch(function () {
+        /* SW registration failed — app still works */
+      });
+    });
+  }
+
+  /* ---- Installable PWA banner (A2HS) ---- */
+  var deferredPrompt = null;
+
+  window.addEventListener('beforeinstallprompt', function (e) {
+    e.preventDefault();
+    deferredPrompt = e;
+    /* Could show a custom install banner here */
+  });
+
+  window.addEventListener('appinstalled', function () {
+    deferredPrompt = null;
+  });
+
+})();