feat(ui): Lists island view with search and nav items

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

src/ClaudeDo.Ui/Views/Islands/ListsIslandView.axaml

@@ -3,6 +3,36 @@
              xmlns:vm="using:ClaudeDo.Ui.ViewModels.Islands"
              x:Class="ClaudeDo.Ui.Views.Islands.ListsIslandView"
              x:DataType="vm:ListsIslandViewModel">
-  <TextBlock Margin="14" Text="Lists (placeholder)"
+  <DockPanel LastChildFill="True">
-             Foreground="{DynamicResource TextDimBrush}"/>
+    <Border DockPanel.Dock="Top" Classes="island-header">
+      <StackPanel Spacing="6" Margin="14,12">
+        <TextBlock Classes="eyebrow" Text="WORKSPACE"/>
+        <TextBlock FontFamily="{DynamicResource SansFamily}" FontSize="18"
+                   FontWeight="SemiBold" Foreground="{DynamicResource TextBrush}"
+                   Text="Lists"/>
+        <TextBox Classes="search" Margin="0,8,0,0" PlaceholderText="Search…"
+                 Text="{Binding SearchText, Mode=TwoWay}"/>
+      </StackPanel>
+    </Border>
+    <ScrollViewer>
+      <ItemsControl ItemsSource="{Binding Items}" Margin="6">
+        <ItemsControl.ItemTemplate>
+          <DataTemplate DataType="vm:ListNavItemViewModel">
+            <Border Classes="list-item" Classes.active="{Binding IsActive}"
+                    Tapped="OnItemTapped">
+              <Grid ColumnDefinitions="20,*,Auto" Margin="10,8">
+                <PathIcon Grid.Column="0" Width="14" Height="14"/>
+                <TextBlock Grid.Column="1" Text="{Binding Name}"
+                           VerticalAlignment="Center" Margin="8,0"
+                           Foreground="{DynamicResource TextBrush}" FontSize="13"/>
+                <TextBlock Grid.Column="2" Text="{Binding Count}"
+                           FontFamily="{DynamicResource MonoFamily}" FontSize="10"
+                           Foreground="{DynamicResource TextFaintBrush}"/>
+              </Grid>
+            </Border>
+          </DataTemplate>
+        </ItemsControl.ItemTemplate>
+      </ItemsControl>
+    </ScrollViewer>
+  </DockPanel>
 </UserControl>

src/ClaudeDo.Ui/Views/Islands/ListsIslandView.axaml.cs

@@ -1,8 +1,17 @@
 using Avalonia.Controls;
+using Avalonia.Interactivity;
+using ClaudeDo.Ui.ViewModels.Islands;
 
 namespace ClaudeDo.Ui.Views.Islands;
 
 public partial class ListsIslandView : UserControl
 {
     public ListsIslandView() { InitializeComponent(); }
+
+    private void OnItemTapped(object? sender, RoutedEventArgs e)
+    {
+        if (sender is Border { DataContext: ListNavItemViewModel item }
+            && DataContext is ListsIslandViewModel vm)
+            vm.SelectCommand.Execute(item);
+    }
 }