fix: 工具市场页面缺少 MainLayout 导入，导航栏不显示

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

frontend/src/views/Tools.vue

@@ -452,6 +452,7 @@
 import { ref, onMounted, computed, watch } from 'vue'
 import { ElMessage } from 'element-plus'
 import { Search, Plus, Edit, Grid, List, Folder, TopRight, InfoFilled, CaretRight, Document } from '@element-plus/icons-vue'
+import MainLayout from '@/components/MainLayout.vue'
 import api from '@/api'
 
 interface Tool {