refactor(P5b-4): 큐·이력 리스트 ItemsSource를 선언적 XAML 바인딩으로 전환

- MainWindow.ActiveQueue/PastResults(ObservableCollection) 노출. XAML: ActiveQueueList/PastResultsList의
  ItemsSource를 Window-relative 바인딩으로. 코드비하인드의 ItemsSource= 명령형 할당 제거.
- 검증: 빌드 0/0, 83 테스트 그린, publish 후 메인 창 크래시 없이 로드(언핸들드 로그 없음).
  리스트 렌더(큐/이력 표시)는 GUI 스모크 권장.

src/Everything2Everything.App/Views/MainWindow.xaml

@@ -438,7 +438,8 @@
                         </Grid>
                         <ScrollViewer x:Name="ActiveQueueScroll" VerticalScrollBarVisibility="Auto"
                                       Padding="24" Visibility="Collapsed">
-                            <ItemsControl x:Name="ActiveQueueList">
+                            <ItemsControl x:Name="ActiveQueueList"
+                                          ItemsSource="{Binding ActiveQueue, RelativeSource={RelativeSource AncestorType=Window}}">
                                 <ItemsControl.ItemTemplate>
                                     <DataTemplate>
                                         <!-- row hover: FsListRowStyle 느낌(투명→surface hover, hairline 보더) + 좌측 형식색 accent bar -->
@@ -527,7 +528,8 @@
                     <!-- Past Results view (default) -->
                     <ScrollViewer x:Name="PastResultsView" VerticalScrollBarVisibility="Auto"
                                   Padding="24">
-                        <ItemsControl x:Name="PastResultsList">
+                        <ItemsControl x:Name="PastResultsList"
+                                      ItemsSource="{Binding PastResults, RelativeSource={RelativeSource AncestorType=Window}}">
                             <ItemsControl.ItemTemplate>
                                 <DataTemplate>
                                     <StackPanel Margin="0,0,0,40">

src/Everything2Everything.App/Views/MainWindow.xaml.cs

@@ -30,6 +30,10 @@ public partial class MainWindow : Wpf.Ui.Controls.FluentWindow
     /// <summary>옵션 패널 XAML이 TwoWay 바인딩하는 옵션 뷰모델(품질·출력폴더).</summary>
     public OptionsViewModel Options => _options;
 
+    /// <summary>Active Queue / Past Results 리스트가 XAML에서 ItemsSource로 바인딩하는 컬렉션.</summary>
+    public ObservableCollection<QueueItem> ActiveQueue => _activeQueue;
+    public ObservableCollection<DateGroup> PastResults => _pastResults;
+
     public ICommand AddFilesCommand { get; }
     public ICommand ProcessQueueCommand { get; }
     public ICommand CloseCommand { get; }
@@ -48,8 +52,7 @@ public partial class MainWindow : Wpf.Ui.Controls.FluentWindow
 
         InitializeComponent();
 
-        ActiveQueueList.ItemsSource = _activeQueue;
+        // ActiveQueueList/PastResultsList의 ItemsSource는 XAML이 ActiveQueue/PastResults에 바인딩(선언적).
-        PastResultsList.ItemsSource = _pastResults;
 
         InitializeOutputFormats();
         LoadHistory();