fix(proxy): 更新预览端口并优化SSE和WS代理配置

- 将预览端口从5173改为8888以避免冲突
- 重构SSE代理配置，简化逻辑并修复连接问题
- 新增WS代理路径，支持WebSocket独立代理

frontend/package.json

@@ -6,7 +6,7 @@
   "scripts": {
     "dev": "vite",
     "build": "tsc -b && vite build",
-    "preview": "vite preview --port 5173"
+    "preview": "vite preview --port 8888"
   },
   "dependencies": {
     "@ant-design/icons": "^5.4.0",