AX Agent 실행 이벤트 재렌더를 배치형으로 조정

- OnAgentEvent가 실행 이벤트마다 본문 전체를 즉시 다시 그리지 않도록 execution history 전용 배치 렌더 타이머를 추가함

- Cowork/Code 실행 중 RenderMessages 호출을 120ms 단위로 묶어 본문 번쩍임과 잦은 로그 재배치를 줄임

- 검증: dotnet build src/AxCopilot/AxCopilot.csproj -c Release -v minimal -p:OutputPath=bin\\verify\\ -p:IntermediateOutputPath=obj\\verify\\ 경고 0 / 오류 0

src/AxCopilot/Views/ChatWindow.xaml.cs

@@ -83,6 +83,7 @@ public partial class ChatWindow : Window
     private readonly DispatcherTimer _gitRefreshTimer;
     private readonly DispatcherTimer _conversationSearchTimer;
     private readonly DispatcherTimer _inputUiRefreshTimer;
+    private readonly DispatcherTimer _executionHistoryRenderTimer;
     private CancellationTokenSource? _gitStatusRefreshCts;
     private int _displayedLength; // 현재 화면에 표시된 글자 수
     private ResourceDictionary? _agentThemeDictionary;
@@ -116,6 +117,7 @@ public partial class ChatWindow : Window
     private int _sessionPostCompactionResponseCount;
     private int _sessionPostCompactionPromptTokens;
     private int _sessionPostCompactionCompletionTokens;
+    private bool _pendingExecutionHistoryAutoScroll;
     private void ApplyQuickActionVisual(Button button, bool active, string activeBg, string activeFg)
     {
         if (button?.Content is not string text)
@@ -233,6 +235,15 @@ public partial class ChatWindow : Window
             RefreshContextUsageVisual();
             RefreshDraftQueueUi();
         };
+        _executionHistoryRenderTimer = new DispatcherTimer { Interval = TimeSpan.FromMilliseconds(120) };
+        _executionHistoryRenderTimer.Tick += (_, _) =>
+        {
+            _executionHistoryRenderTimer.Stop();
+            RenderMessages(preserveViewport: true);
+            if (_pendingExecutionHistoryAutoScroll)
+                AutoScrollIfNeeded();
+            _pendingExecutionHistoryAutoScroll = false;
+        };
 
         KeyDown += ChatWindow_KeyDown;
         UpdateConversationFailureFilterUi();
@@ -8536,6 +8547,8 @@ public partial class ChatWindow : Window
         _cursorTimer.Stop();
         _elapsedTimer.Stop();
         _typingTimer.Stop();
+        _executionHistoryRenderTimer.Stop();
+        _pendingExecutionHistoryAutoScroll = false;
         HideStickyProgress();
         StopRainbowGlow();
         _activeStreamText = null;
@@ -8592,6 +8605,13 @@ public partial class ChatWindow : Window
             _ = Dispatcher.BeginInvoke(new Action(() => StartNextQueuedDraftIfAny()), DispatcherPriority.Background);
     }
 
+    private void ScheduleExecutionHistoryRender(bool autoScroll = true)
+    {
+        _pendingExecutionHistoryAutoScroll |= autoScroll;
+        _executionHistoryRenderTimer.Stop();
+        _executionHistoryRenderTimer.Start();
+    }
+
     // ─── 코워크 에이전트 지원 ────────────────────────────────────────────
 
     private string BuildCoworkSystemPrompt()
@@ -8995,8 +9015,7 @@ public partial class ChatWindow : Window
         AppendConversationExecutionEvent(evt, eventTab);
         if (shouldShowExecutionHistory
             && string.Equals(eventTab, _activeTab, StringComparison.OrdinalIgnoreCase))
-            RenderMessages(preserveViewport: true);
-        AutoScrollIfNeeded();
+            ScheduleExecutionHistoryRender(autoScroll: true);
 
         // 하단 상태바 업데이트
         UpdateStatusBar(evt);