💄 style(DesignPlanningPage): 优化导入语句

- 移除未使用的React默认导入
- 删除未使用的Separator组件导入
- 清理Layout导入中未使用的Palette、Code和Users组件

src/client/home/pages/DesignPlanningPage.tsx

@@ -1,13 +1,9 @@
-import React, { useState } from 'react';
+import { useState } from 'react';
 import { Card, CardContent, CardDescription, CardHeader, CardTitle } from '@/client/components/ui/card';
 import { Button } from '@/client/components/ui/button';
 import { Badge } from '@/client/components/ui/badge';
-import { Separator } from '@/client/components/ui/separator';
 import {
   Layout,
-  Palette,
-  Code,
-  Users,
   Target,
   Clock,
   CheckCircle,