feat(ui): add MergeModalView

src/ClaudeDo.Ui/Views/Modals/MergeModalView.axaml

@@ -0,0 +1,80 @@
+<Window xmlns="https://github.com/avaloniaui"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        xmlns:vm="clr-namespace:ClaudeDo.Ui.ViewModels.Modals"
+        x:Class="ClaudeDo.Ui.Views.Modals.MergeModalView"
+        x:DataType="vm:MergeModalViewModel"
+        Title="Merge worktree"
+        Width="560" Height="420"
+        CanResize="False"
+        WindowStartupLocation="CenterOwner">
+  <Grid Margin="20" RowDefinitions="Auto,Auto,Auto,Auto,Auto,*,Auto">
+
+    <TextBlock Grid.Row="0"
+               Text="{Binding TaskTitle, StringFormat='Merging: {0}'}"
+               FontWeight="SemiBold" Margin="0,0,0,12" />
+
+    <StackPanel Grid.Row="1" Orientation="Vertical" Margin="0,0,0,8">
+      <TextBlock Text="Target branch" Margin="0,0,0,4" />
+      <ComboBox ItemsSource="{Binding Branches}"
+                SelectedItem="{Binding SelectedBranch}"
+                HorizontalAlignment="Stretch"
+                IsEnabled="{Binding !IsBusy}" />
+    </StackPanel>
+
+    <CheckBox Grid.Row="2"
+              Content="Remove worktree after merge"
+              IsChecked="{Binding RemoveWorktree}"
+              IsEnabled="{Binding !IsBusy}"
+              Margin="0,0,0,8" />
+
+    <StackPanel Grid.Row="3" Orientation="Vertical" Margin="0,0,0,8">
+      <TextBlock Text="Commit message" Margin="0,0,0,4" />
+      <TextBox Text="{Binding CommitMessage}"
+               AcceptsReturn="True"
+               TextWrapping="Wrap"
+               Height="70"
+               IsEnabled="{Binding !IsBusy}" />
+    </StackPanel>
+
+    <TextBlock Grid.Row="4"
+               Text="{Binding ErrorMessage}"
+               Foreground="IndianRed"
+               TextWrapping="Wrap"
+               IsVisible="{Binding ErrorMessage, Converter={x:Static ObjectConverters.IsNotNull}}"
+               Margin="0,0,0,8" />
+
+    <Border Grid.Row="5"
+            BorderBrush="IndianRed"
+            BorderThickness="1"
+            Padding="8"
+            IsVisible="{Binding HasConflict}">
+      <StackPanel>
+        <TextBlock Text="Conflicted files:" FontWeight="SemiBold" Margin="0,0,0,4" />
+        <ItemsControl ItemsSource="{Binding ConflictFiles}">
+          <ItemsControl.ItemTemplate>
+            <DataTemplate>
+              <TextBlock Text="{Binding}" />
+            </DataTemplate>
+          </ItemsControl.ItemTemplate>
+        </ItemsControl>
+      </StackPanel>
+    </Border>
+
+    <StackPanel Grid.Row="6" Orientation="Horizontal"
+                HorizontalAlignment="Right" Margin="0,12,0,0">
+      <TextBlock Text="{Binding SuccessMessage}"
+                 Foreground="SeaGreen"
+                 VerticalAlignment="Center"
+                 Margin="0,0,12,0"
+                 IsVisible="{Binding SuccessMessage, Converter={x:Static ObjectConverters.IsNotNull}}" />
+      <Button Content="Cancel"
+              Command="{Binding CancelCommand}"
+              Margin="0,0,8,0" />
+      <Button Content="Merge"
+              Command="{Binding SubmitCommand}"
+              IsDefault="True"
+              Classes="accent" />
+    </StackPanel>
+
+  </Grid>
+</Window>

src/ClaudeDo.Ui/Views/Modals/MergeModalView.axaml.cs

@@ -0,0 +1,19 @@
+using Avalonia.Controls;
+using ClaudeDo.Ui.ViewModels.Modals;
+
+namespace ClaudeDo.Ui.Views.Modals;
+
+public partial class MergeModalView : Window
+{
+    public MergeModalView()
+    {
+        InitializeComponent();
+        DataContextChanged += (_, _) =>
+        {
+            if (DataContext is MergeModalViewModel vm)
+            {
+                vm.CloseAction = () => Close();
+            }
+        };
+    }
+}