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/WizardWindow.xaml

@@ -0,0 +1,95 @@
+<Window x:Class="ClaudeDo.Installer.Views.WizardWindow"
+        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 Installer"
+        Width="720" Height="520"
+        MinWidth="620" MinHeight="460"
+        WindowStartupLocation="CenterScreen"
+        d:DataContext="{d:DesignInstance views:WizardViewModel}"
+        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="Auto"/>
+            <RowDefinition Height="*"/>
+            <RowDefinition Height="Auto"/>
+        </Grid.RowDefinitions>
+
+        <!-- Step Indicator -->
+        <Border Grid.Row="0" Background="{StaticResource IslandBgBrush}"
+                BorderBrush="{StaticResource BorderSubtleBrush}" BorderThickness="0,0,0,1"
+                Padding="20,14">
+            <ItemsControl ItemsSource="{Binding Pages}">
+                <ItemsControl.ItemsPanel>
+                    <ItemsPanelTemplate>
+                        <StackPanel Orientation="Horizontal"/>
+                    </ItemsPanelTemplate>
+                </ItemsControl.ItemsPanel>
+                <ItemsControl.ItemTemplate>
+                    <DataTemplate>
+                        <Border x:Name="StepBorder" CornerRadius="4" Padding="10,5" Margin="0,0,6,0"
+                                BorderThickness="1">
+                            <Border.Background>
+                                <MultiBinding Converter="{StaticResource StepActiveConverter}" ConverterParameter="Background">
+                                    <Binding/>
+                                    <Binding RelativeSource="{RelativeSource AncestorType=Window}" Path="DataContext.CurrentPage"/>
+                                </MultiBinding>
+                            </Border.Background>
+                            <Border.BorderBrush>
+                                <MultiBinding Converter="{StaticResource StepActiveConverter}" ConverterParameter="BorderBrush">
+                                    <Binding/>
+                                    <Binding RelativeSource="{RelativeSource AncestorType=Window}" Path="DataContext.CurrentPage"/>
+                                </MultiBinding>
+                            </Border.BorderBrush>
+                            <TextBlock Text="{Binding Title}" FontSize="12">
+                                <TextBlock.Foreground>
+                                    <MultiBinding Converter="{StaticResource StepActiveConverter}" ConverterParameter="Foreground">
+                                        <Binding/>
+                                        <Binding RelativeSource="{RelativeSource AncestorType=Window}" Path="DataContext.CurrentPage"/>
+                                    </MultiBinding>
+                                </TextBlock.Foreground>
+                            </TextBlock>
+                        </Border>
+                    </DataTemplate>
+                </ItemsControl.ItemTemplate>
+            </ItemsControl>
+        </Border>
+
+        <!-- Page Content -->
+        <Border Grid.Row="1" Padding="24,20">
+            <ContentControl Content="{Binding CurrentPage.View}"/>
+        </Border>
+
+        <!-- Bottom Bar -->
+        <Border Grid.Row="2" 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>
+
+                <!-- Validation error -->
+                <TextBlock Grid.Column="0" Text="{Binding ValidationError}"
+                           Foreground="{StaticResource ErrorBrush}"
+                           VerticalAlignment="Center" FontSize="12"
+                           Visibility="{Binding ValidationError, Converter={StaticResource NullToCollapsedConverter}}"/>
+
+                <Button Grid.Column="1" Content="Back"
+                        Command="{Binding GoBackCommand}"
+                        IsEnabled="{Binding CanGoBack}"
+                        Margin="0,0,8,0" MinWidth="80"/>
+
+                <Button Grid.Column="2" Content="{Binding NextButtonText}"
+                        Command="{Binding GoNextCommand}"
+                        Style="{StaticResource AccentButton}"
+                        MinWidth="100"/>
+            </Grid>
+        </Border>
+    </Grid>
+</Window>