feat: AI对话助手移动端应用

- 智谱 GLM-4.5-Air 大模型接口
- 移动端优化聊天界面
- Capacitor 支持 Android/iOS 打包
- PWA 配置，可添加到主屏幕
- 多对话管理
- 流式输出
- Markdown格式显示
- 复制、重新生成、删除功能
- 端口: 19021

www/manifest.json

@@ -0,0 +1,22 @@
+{
+  "name": "AI助手",
+  "short_name": "AI助手",
+  "description": "AI对话助手移动端应用",
+  "start_url": "/",
+  "display": "standalone",
+  "background_color": "#f7fafc",
+  "theme_color": "#667eea",
+  "orientation": "portrait",
+  "icons": [
+    {
+      "src": "icon-192.png",
+      "sizes": "192x192",
+      "type": "image/png"
+    },
+    {
+      "src": "icon-512.png",
+      "sizes": "512x512",
+      "type": "image/png"
+    }
+  ]
+}