refactor(home): 移除外部链接跳转功能并优化路由导航

- 移除百度链接跳转功能，改为内部路由导航到内容生成页面
- 删除无用的 isChecking 状态和 handleChatClick 处理函数
- 移除菜单项中的 externalLink 属性配置
- 简化侧边栏点击事件处理逻辑，移除外部链接检查代码
- 添加内容生成页面的路由配置

frontend/src/routes/routes.ts

@@ -44,6 +44,7 @@ import SynthFileTask from "@/pages/SynthesisTask/SynthFileTask.tsx";
 import EvaluationDetailPage from "@/pages/DataEvaluation/Detail/TaskDetail.tsx";
 import SynthDataDetail from "@/pages/SynthesisTask/SynthDataDetail.tsx";
 import Home from "@/pages/Home/Home";
+import ContentGenerationPage from "@/pages/ContentGeneration/ContentGenerationPage";
 
 const router = createBrowserRouter([
   {
@@ -152,6 +153,10 @@ const router = createBrowserRouter([
           },
         ],
       },
+      {
+        path: "content-generation",
+        Component: ContentGenerationPage,
+      },
       {
         path: "synthesis/task",
         children: [