feat: PWA支持（manifest+Service Worker缓存+图标，可添加到主屏幕/离线/增量更新）

app/templates/index.html

@@ -4,6 +4,12 @@
   <meta charset="UTF-8">
   <meta name="viewport" content="width=device-width, initial-scale=1.0, viewport-fit=cover">
   <title>{{ app_name }}</title>
+  <link rel="manifest" href="/static/manifest.json">
+  <meta name="theme-color" content="#2563eb">
+  <link rel="apple-touch-icon" href="/static/icons/icon-192.png">
+  <meta name="apple-mobile-web-app-capable" content="yes">
+  <meta name="apple-mobile-web-app-status-bar-style" content="black-translucent">
+  <meta name="apple-mobile-web-app-title" content="资产管理">
   <script src="/static/js/tailwind.js"></script>
   <script>tailwind.config = { darkMode: 'class' };</script>
   <script src="/static/js/vue.global.prod.js"></script>
@@ -19,5 +25,12 @@
   <div id="app"></div>
   <script src="/static/js/api.js"></script>
   <script src="/static/js/app.js"></script>
+  <script>
+    if ('serviceWorker' in navigator) {
+      window.addEventListener('load', function () {
+        navigator.serviceWorker.register('/sw.js').catch(function () {});
+      });
+    }
+  </script>
 </body>
 </html>