Phase 2-3: UI layout, theme switching, CRUD tools, process execution

- Phase 2: MainWindow 3-section layout (sidebar/content/log bar), Dark/Light theme with ThemeHelper, MainViewModel with ObservableProperty/RelayCommand, tool card filtering by search + category

- Phase 3: ToolEditWindow for add/edit tools, ProcessExecutionService (Process.Start + error handling), double-click + right-click context menu (run/edit), path browse dialog

- Bugfix: ContextMenu commands now use PlacementTarget.Tag binding (ContextMenu in separate visual tree)

- Bugfix: StaticResource converters moved to XAML before DataTemplate to fix XamlParseException on tool card render

- Bugfix: Pure filenames (no path separators) treated as PATH commands, not marked invalid

- Bugfix: RefreshData preserves SelectedCategory; Load() catches all exceptions; Save() wrapped in try-catch; auto-scroll log to newest entry

- Tests: xUnit project with 55 tests covering models, services, converters, and view models

PersonalToolBox/Views/MainWindow.xaml.cs

@@ -1,11 +1,63 @@
-using System.Windows;
+using System;
+using System.Collections.Specialized;
+using System.Globalization;
+using System.Windows;
+using System.Windows.Data;
+using PersonalToolBox.ViewModels;
 
 namespace PersonalToolBox.Views;
 
 public partial class MainWindow : Window
 {
-    public MainWindow()
+    private readonly MainViewModel _viewModel;
+
+    public MainWindow(MainViewModel viewModel)
     {
         InitializeComponent();
+
+        _viewModel = viewModel;
+        DataContext = viewModel;
+
+        viewModel.Logs.CollectionChanged += OnLogsCollectionChanged;
+    }
+
+    private void OnLogsCollectionChanged(object? sender, NotifyCollectionChangedEventArgs e)
+    {
+        if (e.Action == NotifyCollectionChangedAction.Add && LogListBox.Items.Count > 0)
+        {
+            Dispatcher.BeginInvoke(new Action(() =>
+            {
+                LogListBox.ScrollIntoView(LogListBox.Items[^1]);
+            }), System.Windows.Threading.DispatcherPriority.Background);
+        }
     }
 }
+
+/// <summary>
+/// bool → double: true=1.0, false=0.4 (工具卡片失效时置灰)
+/// </summary>
+public class BoolToOpacityConverter : IValueConverter
+{
+    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
+    {
+        return value is bool b && b ? 1.0 : 0.4;
+    }
+
+    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+        => throw new NotImplementedException();
+}
+
+/// <summary>
+/// string → string: 取字符串首字符作为图标占位
+/// </summary>
+public class FirstCharConverter : IValueConverter
+{
+    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
+    {
+        var s = value as string;
+        return string.IsNullOrEmpty(s) ? "?" : s[0].ToString();
+    }
+
+    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+        => throw new NotImplementedException();
+}