fix(ui): make batch summary stop button respond immediately

Previously clicking stop would only take effect after the current LLM
request finished. Now the UI state updates instantly while the in-flight
request completes silently in the background.

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

src/components/common/ChatRecord/BatchSummaryModal.vue

@@ -330,9 +330,10 @@ async function startGenerate() {
   }
 }
 
-// 停止生成
+// 停止生成：立即更新 UI 状态，后台请求自然结束不影响
 function stopGenerate() {
   shouldStop.value = true
+  isGenerating.value = false
 }
 
 // 关闭弹窗