Refactor launcher startup, logging & host resolution

Improve launcher startup flow, logging, and host resolution. Key changes: add detailed startup logging and standardized preview messages; unify CLI vs GUI handling and error/result reporting (write result file when requested); refactor DeploymentLocator to a more robust host resolution (new HostResolutionResult, explicit/portable/published/debug resolution paths, legacy fallback); overhaul LauncherFlowCoordinator to better handle IPC stages, activation retries, window lifecycle, plugin/update flows and error reporting; add CommandContext helpers (IsGui/IsPreview/ExplicitAppRoot) and JSON context options; tighten async usage and ConfigureAwait calls; add better UI error handling and consistent exit codes. Several UX/debug conveniences and robustness fixes included.

LanMountainDesktop.Launcher/Services/WelcomeOobeStep.cs

@@ -0,0 +1,42 @@
+using Avalonia.Threading;
+using LanMountainDesktop.Launcher.Views;
+
+namespace LanMountainDesktop.Launcher.Services;
+
+internal sealed class WelcomeOobeStep : IOobeStep
+{
+    private readonly OobeStateService _oobeStateService;
+
+    public WelcomeOobeStep(OobeStateService oobeStateService)
+    {
+        _oobeStateService = oobeStateService;
+    }
+
+    public async Task RunAsync(CancellationToken cancellationToken)
+    {
+        cancellationToken.ThrowIfCancellationRequested();
+
+        OobeWindow? window = null;
+        await Dispatcher.UIThread.InvokeAsync(() =>
+        {
+            window = new OobeWindow();
+            window.Show();
+        });
+
+        if (window is null)
+        {
+            return;
+        }
+
+        await window.WaitForEnterAsync().ConfigureAwait(false);
+        _oobeStateService.MarkCompleted();
+
+        await Dispatcher.UIThread.InvokeAsync(() =>
+        {
+            if (window.IsVisible)
+            {
+                window.Close();
+            }
+        });
+    }
+}