feat(installer): add WPF installer/configurator project

Standalone WPF app (ClaudeDo.Installer) that handles full installation
and ongoing configuration of ClaudeDo. Two modes: wizard for first run,
tabbed settings panel for subsequent launches. Page-based extensibility
via IInstallerPage interface — adding new config sections requires only
one new class.

Install pipeline: dotnet publish, deploy binaries, write configs, init
DB (via SchemaInitializer from ClaudeDo.Data), register Windows Service,
create shortcuts. Dark theme matching the Avalonia app (forest teal accent).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/ClaudeDo.Installer/Views/SettingsWindow.xaml

@@ -0,0 +1,92 @@
+<Window x:Class="ClaudeDo.Installer.Views.SettingsWindow"
+        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        xmlns:views="clr-namespace:ClaudeDo.Installer.Views"
+        Title="ClaudeDo Settings"
+        Width="720" Height="520"
+        MinWidth="620" MinHeight="460"
+        WindowStartupLocation="CenterScreen"
+        d:DataContext="{d:DesignInstance views:SettingsViewModel}"
+        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+        mc:Ignorable="d">
+
+    <Grid>
+        <Grid.RowDefinitions>
+            <RowDefinition Height="*"/>
+            <RowDefinition Height="Auto"/>
+        </Grid.RowDefinitions>
+
+        <!-- Main content area -->
+        <Grid Grid.Row="0">
+            <Grid.ColumnDefinitions>
+                <ColumnDefinition Width="180"/>
+                <ColumnDefinition Width="Auto"/>
+                <ColumnDefinition Width="*"/>
+            </Grid.ColumnDefinitions>
+
+            <!-- Sidebar -->
+            <Border Grid.Column="0" Background="{StaticResource SidebarBgBrush}"
+                    Padding="8,12">
+                <ListBox ItemsSource="{Binding Pages}"
+                         SelectedItem="{Binding SelectedPage}"
+                         HorizontalContentAlignment="Stretch">
+                    <ListBox.ItemTemplate>
+                        <DataTemplate>
+                            <StackPanel Orientation="Horizontal">
+                                <TextBlock Text="{Binding Icon}" FontSize="14" Margin="0,0,8,0"
+                                           VerticalAlignment="Center"/>
+                                <TextBlock Text="{Binding Title}" FontSize="13"/>
+                            </StackPanel>
+                        </DataTemplate>
+                    </ListBox.ItemTemplate>
+                </ListBox>
+            </Border>
+
+            <!-- Separator -->
+            <Border Grid.Column="1" Width="1" Background="{StaticResource BorderSubtleBrush}"/>
+
+            <!-- Page content -->
+            <Border Grid.Column="2" Padding="24,20">
+                <ContentControl Content="{Binding SelectedPage.View}"/>
+            </Border>
+        </Grid>
+
+        <!-- Bottom Bar -->
+        <Border Grid.Row="1" Background="{StaticResource IslandBgBrush}"
+                BorderBrush="{StaticResource BorderSubtleBrush}" BorderThickness="0,1,0,0"
+                Padding="20,12">
+            <Grid>
+                <Grid.ColumnDefinitions>
+                    <ColumnDefinition Width="*"/>
+                    <ColumnDefinition Width="Auto"/>
+                    <ColumnDefinition Width="Auto"/>
+                </Grid.ColumnDefinitions>
+
+                <!-- Status message -->
+                <TextBlock Grid.Column="0" Text="{Binding StatusMessage}"
+                           VerticalAlignment="Center" FontSize="12">
+                    <TextBlock.Style>
+                        <Style TargetType="TextBlock">
+                            <Setter Property="Foreground" Value="{StaticResource AccentBrush}"/>
+                            <Style.Triggers>
+                                <DataTrigger Binding="{Binding IsStatusError}" Value="True">
+                                    <Setter Property="Foreground" Value="{StaticResource ErrorBrush}"/>
+                                </DataTrigger>
+                            </Style.Triggers>
+                        </Style>
+                    </TextBlock.Style>
+                </TextBlock>
+
+                <Button Grid.Column="1" Content="Close"
+                        Command="{Binding CloseCommand}"
+                        Margin="0,0,8,0" MinWidth="80"/>
+
+                <Button Grid.Column="2" Content="Save &amp; Apply"
+                        Command="{Binding ApplyCommand}"
+                        Style="{StaticResource AccentButton}"
+                        MinWidth="100"/>
+            </Grid>
+        </Border>
+    </Grid>
+</Window>