feat(backtest): 失败与已停止的回测任务支持在列表中删除

操作列删除按钮对 STOPPED、FAILED 状态也显示，与详情页一致。

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: WrBug

frontend/src/pages/BacktestList.tsx

@@ -650,7 +650,7 @@ const BacktestList: React.FC = () => {
               {t('backtest.retry')}
             </Button>
           )}
-          {(record.status === 'PENDING' || record.status === 'COMPLETED') && (
+          {(record.status === 'PENDING' || record.status === 'COMPLETED' || record.status === 'STOPPED' || record.status === 'FAILED') && (
             <Button
               type="link"
               size="small"