feat: register service worker in index.html so PWA cache busting works

static/index.html

@@ -7030,6 +7030,22 @@
     };
     return map[name] || name;
   }
+    // ── Register service worker for PWA caching ──────────────────────
+    if ('serviceWorker' in navigator) {
+      navigator.serviceWorker.register('/sw.js').then(reg => {
+        reg.onupdatefound = () => {
+          const installing = reg.installing;
+          if (installing) {
+            installing.onstatechange = () => {
+              if (installing.state === 'installed' && navigator.serviceWorker.controller) {
+                console.log('PWA update available — reload to activate');
+              }
+            };
+          }
+        };
+      }).catch(e => console.warn('SW registration failed:', e));
+    }
+
     document.addEventListener('DOMContentLoaded', () => {
       initAuth();
       initGPS();