fix service worker logic for new mih updates

mih_ui/web/flutter_bootstrap.js

@@ -1,5 +1,49 @@
 {{flutter_js}}
 {{flutter_build_config}}
 
-// This is the default loader that Flutter 3.24 expects
-_flutter.loader.load();
+const serviceWorkerVersion = '{{flutter_service_worker_version}}';
+
+if ('serviceWorker' in navigator) {
+  window.addEventListener('load', function () {
+    const serviceWorkerUrl = 'flutter_service_worker.js?v=' + serviceWorkerVersion;
+    
+    // Manually register here so we can attach custom update listeners
+    navigator.serviceWorker.register(serviceWorkerUrl).then((reg) => {
+      if (reg.waiting) {
+        showUpdatePrompt(reg);
+      }
+
+      reg.addEventListener('updatefound', () => {
+        const newWorker = reg.installing;
+        newWorker.addEventListener('statechange', () => {
+          if (newWorker.state === 'installed' && navigator.serviceWorker.controller) {
+            showUpdatePrompt(reg);
+          }
+        });
+      });
+    });
+
+    let refreshing = false;
+    navigator.serviceWorker.addEventListener('controllerchange', () => {
+      if (!refreshing) {
+        refreshing = true;
+        window.location.reload();
+      }
+    });
+  });
+}
+
+function showUpdatePrompt(reg) {
+  if (confirm('A new version of MIH is available. Refresh now to update?')) {
+    reg.unregister().then(function () {
+      window.location.reload(); // Bypass cache and reload
+    });
+  }
+}
+
+// Initialize Flutter and pass the service worker version
+_flutter.loader.load({
+  serviceWorkerSettings: {
+    serviceWorkerVersion: serviceWorkerVersion
+  }
+});