feat(ui): open editor on double-click for lists and tasks

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

src/ClaudeDo.Ui/Views/MainWindow.axaml

@@ -31,7 +31,7 @@
                          Margin="4">
                     <ListBox.ItemTemplate>
                         <DataTemplate x:DataType="vm:ListItemViewModel">
-                            <StackPanel Margin="4,2">
+                            <StackPanel Margin="4,2" DoubleTapped="OnListItemDoubleTapped">
                                 <TextBlock Text="{Binding Name}" FontWeight="SemiBold"/>
                                 <TextBlock Text="{Binding WorkingDir}" FontSize="10" Foreground="Gray"
                                            IsVisible="{Binding WorkingDir, Converter={x:Static ObjectConverters.IsNotNull}}"/>