feat: Add PWA support with manifest and ServiceWorker integration

- Mounted static files directory to serve PWA assets like manifest.json and ServiceWorker scripts.
- Updated `auth.html` and `keys_status.html` templates:
  - Added `<link>` for manifest and icons to support Progressive Web App (PWA) features.
  - Added meta tags for theme color and Apple web app capabilities.
  - Integrated ServiceWorker registration script for offline capabilities.

app/templates/keys_status.html

@@ -4,6 +4,12 @@
     <meta charset="UTF-8">
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
     <title>API密钥状态</title>
+    <link rel="manifest" href="/static/manifest.json">
+    <meta name="theme-color" content="#764ba2">
+    <meta name="apple-mobile-web-app-capable" content="yes">
+    <meta name="apple-mobile-web-app-status-bar-style" content="black">
+    <meta name="apple-mobile-web-app-title" content="GBalance">
+    <link rel="icon" href="/static/icons/icon-192x192.png">
     <link href="https://fonts.googleapis.com/css2?family=Roboto:wght@300;400;700&display=swap" rel="stylesheet">
     <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/6.0.0/css/all.min.css">
     <style>
@@ -461,5 +467,18 @@
             }
         });
     </script>
+    <script>
+        if ('serviceWorker' in navigator) {
+            window.addEventListener('load', () => {
+                navigator.serviceWorker.register('/static/service-worker.js')
+                    .then(registration => {
+                        console.log('ServiceWorker注册成功:', registration.scope);
+                    })
+                    .catch(error => {
+                        console.log('ServiceWorker注册失败:', error);
+                    });
+            });
+        }
+    </script>
 </body>
 </html>