新增：数据库可见性过滤与连接管理增强

功能：
- 支持配置 MySQL/MongoDB 可见数据库列表
- 连接删除时自动清理关联数据并关闭连接池
- 新增加载数据库列表 API
- 数据库错误提示优化

改进：
- 代码简化：消除重复的表单验证和密码处理逻辑
- ResultPanel 表格高度计算重构
- 删除调试日志和临时文件

后端：
- 新增 VisibleDatabases 字段到连接模型
- DeleteConnection 使用事务确保数据一致性
- LoadAllDatabases 支持 MySQL/MongoDB 数据库列表加载

web/src/App.vue

@@ -72,17 +72,16 @@
 </template>
 
 <script setup>
-import { computed, watch, ref, onMounted, onUnmounted } from 'vue'
-import { IconSettings } from '@arco-design/web-vue/es/icon'
-import { Message } from '@arco-design/web-vue'
+import {computed, onMounted, onUnmounted, ref, watch} from 'vue'
+import {IconSettings} from '@arco-design/web-vue/es/icon'
 import DbCli from './views/db-cli/index.vue'
 import ThemeToggle from './components/ThemeToggle.vue'
 import FileSystem from './components/FileSystem/index.vue'
 import SettingsPanel from './components/SettingsPanel.vue'
 import UpdateNotification from './components/UpdateNotification.vue'
-import { useUpdateStore } from './stores/update'
-import { useConfigStore } from './stores/config'
-import { preloadCommonLanguages } from './utils/codeMirrorLoader'
+import {useUpdateStore} from './stores/update'
+import {useConfigStore} from './stores/config'
+import {preloadCommonLanguages} from './utils/codeMirrorLoader'
 
 // 存储键
 const ACTIVE_TAB_STORAGE_KEY = 'app-active-tab'