fix: correct icon name and remove unused import

- Change BuildingOutlined to BuildOutlined (correct export)
- Remove unused React import

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/pages/index.tsx

@@ -1,7 +1,6 @@
-import React from 'react';
 import { useMyState } from '@/common';
 import {
-  BuildingOutlined,
+  BuildOutlined,
   ImportOutlined,
   TeamOutlined,
 } from '@ant-design/icons';
@@ -13,7 +12,7 @@ export default function Index() {
 
   const quickActions = [
     {
-      icon: <BuildingOutlined />,
+      icon: <BuildOutlined />,
       title: '添加机构',
       description: '快速创建新的机构',
       themeColor: '#1890ff',