AX Agent 설정창 오픈 안정화: ToggleSwitch 전역 리소스화 및 테마 주입 경로 분리

- App.xaml: ToggleSwitch 스타일을 전역 리소스로 추가해 ChatWindow 초기화 시 StaticResource 누락 예외를 방지\n- ChatWindow.xaml.cs: Agent 설정창 오픈 시 창 전체 Resources 병합을 제거하고 AX Agent 테마 사전만 안전 주입하도록 변경\n- ChatWindow.xaml.cs: ApplyAgentThemeResources와 설정창 주입 경로에서 공통 URI 생성 로직(BuildAgentThemeDictionaryUri)으로 중복 제거\n- README.md / docs/DEVELOPMENT.md: 2026-04-04 17:12(KST) 기준 변경 이력 및 검증 결과 동기화\n- 검증: dotnet build(경고0/오류0), dotnet test 필터 59 passed

src/AxCopilot/App.xaml

@@ -19,6 +19,42 @@
             <converters:WarningSubtitleColorConverter x:Key="WarningSubtitleColorConverter"/>
             <converters:ClipboardThumbnailConverter x:Key="ClipboardThumbnailConverter"/>
             <converters:ClipboardHasImageConverter x:Key="ClipboardHasImageConverter"/>
+
+            <!-- 전역 토글 스위치: 창별 리소스 누락 시에도 동일 스타일 보장 -->
+            <Style x:Key="ToggleSwitch" TargetType="CheckBox">
+                <Setter Property="Cursor" Value="Hand"/>
+                <Setter Property="Template">
+                    <Setter.Value>
+                        <ControlTemplate TargetType="CheckBox">
+                            <Grid Width="46" Height="26" VerticalAlignment="Center">
+                                <Border x:Name="Track"
+                                        Width="46"
+                                        Height="26"
+                                        CornerRadius="13"
+                                        Background="#D0D0E0"/>
+                                <Ellipse x:Name="Thumb"
+                                         Width="20"
+                                         Height="20"
+                                         Margin="3,0,0,0"
+                                         HorizontalAlignment="Left"
+                                         VerticalAlignment="Center"
+                                         Fill="White">
+                                    <Ellipse.Effect>
+                                        <DropShadowEffect BlurRadius="5" ShadowDepth="1" Opacity="0.25" Direction="270"/>
+                                    </Ellipse.Effect>
+                                </Ellipse>
+                            </Grid>
+                            <ControlTemplate.Triggers>
+                                <Trigger Property="IsChecked" Value="True">
+                                    <Setter TargetName="Track" Property="Background" Value="{DynamicResource AccentColor}"/>
+                                    <Setter TargetName="Thumb" Property="HorizontalAlignment" Value="Right"/>
+                                    <Setter TargetName="Thumb" Property="Margin" Value="0,0,3,0"/>
+                                </Trigger>
+                            </ControlTemplate.Triggers>
+                        </ControlTemplate>
+                    </Setter.Value>
+                </Setter>
+            </Style>
         </ResourceDictionary>
     </Application.Resources>
 </Application>

src/AxCopilot/Views/ChatWindow.xaml.cs

@@ -803,13 +803,7 @@ public partial class ChatWindow : Window
 
     private void ApplyAgentThemeResources()
     {
-        var selected = (_settings.Settings.Llm.AgentTheme ?? "system").Trim().ToLowerInvariant();
-        var effective = selected switch
-        {
-            "light" => "AgentLight",
-            "dark" => "AgentDark",
-            _ => IsSystemDarkTheme() ? "AgentDark" : "AgentLight",
-        };
+        var themeUri = BuildAgentThemeDictionaryUri();
 
         try
         {
@@ -818,7 +812,7 @@ public partial class ChatWindow : Window
 
             _agentThemeDictionary = new ResourceDictionary
             {
-                Source = new Uri($"pack://application:,,,/Themes/{effective}.xaml"),
+                Source = themeUri,
             };
             Resources.MergedDictionaries.Insert(0, _agentThemeDictionary);
         }
@@ -828,6 +822,18 @@ public partial class ChatWindow : Window
         }
     }
 
+    private Uri BuildAgentThemeDictionaryUri()
+    {
+        var selected = (_settings.Settings.Llm.AgentTheme ?? "system").Trim().ToLowerInvariant();
+        var effective = selected switch
+        {
+            "light" => "AgentLight",
+            "dark" => "AgentDark",
+            _ => IsSystemDarkTheme() ? "AgentDark" : "AgentLight",
+        };
+        return new Uri($"pack://application:,,,/Themes/{effective}.xaml");
+    }
+
     private static bool IsSystemDarkTheme()
     {
         try
@@ -12974,11 +12980,14 @@ public partial class ChatWindow : Window
         win.Closed += (_, _) => _agentSettingsWindow = null;
         try
         {
-            win.Resources.MergedDictionaries.Add(Resources);
+            win.Resources.MergedDictionaries.Insert(0, new ResourceDictionary
+            {
+                Source = BuildAgentThemeDictionaryUri(),
+            });
         }
         catch
         {
-            // 리소스 병합 실패 시에도 설정창 자체는 열리도록 유지
+            // 테마 사전 로드 실패 시에도 설정창 자체는 열리도록 유지
         }
 
         bool changed;