✨ feat(query-editor): 支持还原 SQL 美化前内容

- 美化 SQL 前保存最近一次原始内容快照
- 在格式设置菜单提供还原上次美化入口
- 持久化查询标签页的美化恢复快照
- 补充编辑器与状态恢复回归测试

frontend/src/components/QueryEditor.tsx

@@ -3948,12 +3948,22 @@ const QueryEditor: React.FC<{ tab: TabData; isActive?: boolean }> = ({ tab, isAc
                   ? connectionsRef.current.find(c => c.id === tabConnectionId)
                   : undefined);
           const formatterLanguage = resolveQueryEditorFormatterLanguage(conn);
-          const formatted = format(getCurrentQuery(), { language: formatterLanguage, keywordCase: sqlFormatOptions.keywordCase });
+          const sourceSql = getCurrentQuery();
+          const formatted = format(sourceSql, { language: formatterLanguage, keywordCase: sqlFormatOptions.keywordCase });
+          if (sourceSql === formatted) {
+              return;
+          }
+          updateQueryTabDraft(tab.id, {
+              formatRestoreSnapshot: {
+                  query: sourceSql,
+                  createdAt: Date.now(),
+              },
+          });
           const editor = editorRef.current;
           const monaco = monacoRef.current;
           const model = editor?.getModel?.();
           if (editor && monaco && model) {
-              const currentValue = String(model.getValue?.() || '');
+              const currentValue = String(model.getValue?.() || sourceSql);
               if (currentValue === formatted) {
                   return;
               }
@@ -3977,6 +3987,21 @@ const QueryEditor: React.FC<{ tab: TabData; isActive?: boolean }> = ({ tab, isAc
       }
   };
 
+  const handleRestoreLastFormat = () => {
+      const previousQuery = tab.formatRestoreSnapshot?.query;
+      if (!previousQuery) {
+          void message.info('没有可还原的美化前 SQL');
+          return;
+      }
+      syncQueryToEditor(previousQuery);
+      updateQueryTabDraft(tab.id, {
+          query: previousQuery,
+          formatRestoreSnapshot: undefined,
+      });
+      refreshObjectDecorations();
+      void message.success('已还原到美化前 SQL');
+  };
+
   const handleAIAction = (action: 'generate' | 'explain' | 'optimize' | 'schema') => {
       const editor = editorRef.current;
       const selection = editor?.getModel()?.getValueInRange(editor.getSelection()) || '';
@@ -4013,6 +4038,13 @@ const QueryEditor: React.FC<{ tab: TabData; isActive?: boolean }> = ({ tab, isAc
           onClick: () => setSqlFormatOptions({ keywordCase: 'lower' }) 
       },
       { type: 'divider' },
+      {
+          key: 'restore-last-format',
+          label: '还原上次美化',
+          disabled: !tab.formatRestoreSnapshot?.query,
+          onClick: handleRestoreLastFormat,
+      },
+      { type: 'divider' },
       {
           key: 'snippet-settings',
           label: '代码片段管理...',