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/App.xaml

@@ -0,0 +1,15 @@
+<Application x:Class="ClaudeDo.Installer.App"
+             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:core="clr-namespace:ClaudeDo.Installer.Core">
+    <Application.Resources>
+        <ResourceDictionary>
+            <ResourceDictionary.MergedDictionaries>
+                <ResourceDictionary Source="Theme/DarkTheme.xaml"/>
+            </ResourceDictionary.MergedDictionaries>
+            <core:NullToCollapsedConverter x:Key="NullToCollapsedConverter"/>
+            <core:StepActiveConverter x:Key="StepActiveConverter"/>
+            <BooleanToVisibilityConverter x:Key="BoolToVisConverter"/>
+        </ResourceDictionary>
+    </Application.Resources>
+</Application>