feat(ui): tasks island with rows, chips, add-task, selection

TaskRowView with status chip (EqStatus converter + parameter),
StrikeIfTrue, NotNullToBool converters. TasksIslandView with header,
add-task TextBox (Enter=AddCommand), ItemsControl + flat Button for
selection. Converters registered in App.axaml.

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

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

@@ -1,8 +1,47 @@
 <UserControl xmlns="https://github.com/avaloniaui"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
              xmlns:vm="using:ClaudeDo.Ui.ViewModels.Islands"
+             xmlns:islands="using:ClaudeDo.Ui.Views.Islands"
              x:Class="ClaudeDo.Ui.Views.Islands.TasksIslandView"
              x:DataType="vm:TasksIslandViewModel">
-  <TextBlock Margin="14" Text="Tasks (placeholder)"
-             Foreground="{DynamicResource TextDimBrush}"/>
+  <DockPanel LastChildFill="True">
+
+    <!-- Header -->
+    <Border DockPanel.Dock="Top" Classes="island-header">
+      <StackPanel Margin="18,14" Spacing="4">
+        <TextBlock Classes="eyebrow" Text="{Binding HeaderEyebrow}"/>
+        <TextBlock FontFamily="{DynamicResource SansFamily}" FontSize="24"
+                   FontWeight="SemiBold" Foreground="{DynamicResource TextBrush}"
+                   Text="{Binding HeaderTitle}"/>
+        <TextBlock FontFamily="{DynamicResource MonoFamily}" FontSize="11"
+                   Foreground="{DynamicResource TextMuteBrush}" Text="{Binding Subtitle}"/>
+      </StackPanel>
+    </Border>
+
+    <!-- Add-task row -->
+    <Border DockPanel.Dock="Top" Margin="18,8,18,4">
+      <TextBox Watermark="Add a task…" Text="{Binding NewTaskTitle, Mode=TwoWay}">
+        <TextBox.KeyBindings>
+          <KeyBinding Gesture="Enter" Command="{Binding AddCommand}"/>
+        </TextBox.KeyBindings>
+      </TextBox>
+    </Border>
+
+    <!-- Task list -->
+    <ScrollViewer>
+      <ItemsControl ItemsSource="{Binding Items}" Margin="10,4">
+        <ItemsControl.ItemTemplate>
+          <DataTemplate DataType="vm:TaskRowViewModel">
+            <Button Classes="flat" HorizontalAlignment="Stretch"
+                    HorizontalContentAlignment="Stretch"
+                    Command="{Binding $parent[ItemsControl].DataContext.SelectCommand}"
+                    CommandParameter="{Binding}">
+              <islands:TaskRowView/>
+            </Button>
+          </DataTemplate>
+        </ItemsControl.ItemTemplate>
+      </ItemsControl>
+    </ScrollViewer>
+
+  </DockPanel>
 </UserControl>