feat: 添加推送通知功能，支持订阅和发送通知

Web/public/service-worker.js

@@ -107,17 +107,29 @@ self.addEventListener('sync', (event) => {
 // 推送通知
 self.addEventListener('push', (event) => {
   console.log('[Service Worker] 收到推送消息');
+  let data = { title: '账单管理', body: '您有新的消息', url: '/', icon: '/icons/icon-192x192.png' };
+  
+  if (event.data) {
+    try {
+      const json = event.data.json();
+      data = { ...data, ...json };
+    } catch (e) {
+      data.body = event.data.text();
+    }
+  }
+
   const options = {
-    body: event.data ? event.data.text() : '您有新的账单消息',
-    icon: '/icons/icon-192x192.png',
+    body: data.body,
+    icon: data.icon,
     badge: '/icons/icon-72x72.png',
     vibrate: [200, 100, 200],
     tag: 'emailbill-notification',
-    requireInteraction: false
+    requireInteraction: false,
+    data: { url: data.url }
   };
 
   event.waitUntil(
-    self.registration.showNotification('账单管理', options)
+    self.registration.showNotification(data.title, options)
   );
 });
 
@@ -125,8 +137,21 @@ self.addEventListener('push', (event) => {
 self.addEventListener('notificationclick', (event) => {
   console.log('[Service Worker] 通知被点击');
   event.notification.close();
+  const urlToOpen = event.notification.data?.url || '/';
   event.waitUntil(
-    clients.openWindow('/')
+    clients.matchAll({ type: 'window', includeUncontrolled: true }).then((windowClients) => {
+      // 如果已经打开了该 URL，则聚焦
+      for (let i = 0; i < windowClients.length; i++) {
+        const client = windowClients[i];
+        if (client.url === urlToOpen && 'focus' in client) {
+          return client.focus();
+        }
+      }
+      // 否则打开新窗口
+      if (clients.openWindow) {
+        return clients.openWindow(urlToOpen);
+      }
+    })
   );
 });