🐛 fix(query-editor): 修复选择器与事务提示浮层

- host 和数据库下拉选项关闭原生 title，避免和自定义 Tooltip 重复显示
- 事务模式说明默认向上弹出，并保留边界自动避让
- 移除下拉打开时强制隐藏事务说明的状态控制
- 补充工具栏和事务设置回归断言

frontend/src/components/QueryEditorToolbar.tsx

@@ -60,6 +60,7 @@ const FULL_NAME_TOOLTIP_DELAY_SECONDS = 1;
 type FullNameSelectOption = {
   label: string;
   value: string;
+  title: string;
   fullName: string;
 };
 
@@ -120,11 +121,13 @@ const QueryEditorToolbar: React.FC<QueryEditorToolbarProps> = ({
     queryCapableConnections.map((connection) => ({
       label: connection.name,
       value: connection.id,
+      title: "",
       fullName: connection.name,
     }));
   const databaseSelectOptions: FullNameSelectOption[] = dbList.map((db) => ({
     label: db,
     value: db,
+    title: "",
     fullName: db,
   }));
   const toggleResultPanelShortcutLabel =