[Phase 39] FontFamily 캐싱 + LauncherWindow 파셜 클래스 분할

- ThemeResourceHelper에 CascadiaCode/ConsolasCode/ConsolasCourierNew 정적 필드 추가
- 25개 파일, 89개 new FontFamily(...) 호출을 정적 캐시 참조로 교체
- LauncherWindow.xaml.cs (1,563줄) → 5개 파셜 파일로 분할 (63% 감소)
  - LauncherWindow.Theme.cs (116줄): ApplyTheme, 커스텀 딕셔너리 빌드
  - LauncherWindow.Animations.cs (153줄): 무지개 글로우, 애니메이션 헬퍼
  - LauncherWindow.Keyboard.cs (593줄): 단축키 20종, ShowToast, IME 검색
  - LauncherWindow.Shell.cs (177줄): Shell32, SendToRecycleBin, 클릭 핸들러
- 빌드: 경고 0, 오류 0

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/AxCopilot/Views/DockBarWindow.xaml.cs

@@ -165,7 +165,7 @@ public partial class DockBarWindow : Window
                     var cpuPanel = new StackPanel { Orientation = Orientation.Horizontal, VerticalAlignment = VerticalAlignment.Center };
                     cpuPanel.Children.Add(new TextBlock
                     {
-                        Text = "\uE950", FontFamily = new FontFamily("Segoe MDL2 Assets"),
+                        Text = "\uE950", FontFamily = ThemeResourceHelper.SegoeMdl2,
                         FontSize = 11, Foreground = accentBrush,
                         VerticalAlignment = VerticalAlignment.Center, Margin = new Thickness(0, 0, 3, 0)
                     });
@@ -180,7 +180,7 @@ public partial class DockBarWindow : Window
                     var ramPanel = new StackPanel { Orientation = Orientation.Horizontal, VerticalAlignment = VerticalAlignment.Center };
                     ramPanel.Children.Add(new TextBlock
                     {
-                        Text = "\uE7F4", FontFamily = new FontFamily("Segoe MDL2 Assets"),
+                        Text = "\uE7F4", FontFamily = ThemeResourceHelper.SegoeMdl2,
                         FontSize = 11, Foreground = accentBrush,
                         VerticalAlignment = VerticalAlignment.Center, Margin = new Thickness(0, 0, 3, 0)
                     });
@@ -199,7 +199,7 @@ public partial class DockBarWindow : Window
                     var inputPanel = new StackPanel { Orientation = Orientation.Horizontal };
                     inputPanel.Children.Add(new TextBlock
                     {
-                        Text = "\uE721", FontFamily = new FontFamily("Segoe MDL2 Assets"),
+                        Text = "\uE721", FontFamily = ThemeResourceHelper.SegoeMdl2,
                         FontSize = 11, Foreground = accentBrush,
                         VerticalAlignment = VerticalAlignment.Center, Margin = new Thickness(0, 0, 5, 0)
                     });
@@ -246,7 +246,7 @@ public partial class DockBarWindow : Window
         border.Child = new TextBlock
         {
             Text = icon,
-            FontFamily = new FontFamily("Segoe MDL2 Assets"),
+            FontFamily = ThemeResourceHelper.SegoeMdl2,
             FontSize = 14, Foreground = foreground,
             HorizontalAlignment = HorizontalAlignment.Center,
             VerticalAlignment = VerticalAlignment.Center,