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/Steps/InitDatabaseStep.cs

@@ -0,0 +1,28 @@
+using ClaudeDo.Data;
+using ClaudeDo.Installer.Core;
+
+namespace ClaudeDo.Installer.Steps;
+
+public sealed class InitDatabaseStep : IInstallStep
+{
+    public string Name => "Initialize Database";
+
+    public Task<StepResult> ExecuteAsync(InstallContext ctx, IProgress<string> progress, CancellationToken ct)
+    {
+        try
+        {
+            var expandedPath = Paths.Expand(ctx.DbPath);
+            progress.Report($"Initializing database at {expandedPath}");
+
+            var factory = new SqliteConnectionFactory(expandedPath);
+            SchemaInitializer.Apply(factory);
+
+            progress.Report("Schema applied successfully");
+            return Task.FromResult(StepResult.Ok());
+        }
+        catch (Exception ex)
+        {
+            return Task.FromResult(StepResult.Fail(ex.Message));
+        }
+    }
+}