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/CommandContext.cs

@@ -4,6 +4,17 @@ namespace LanMountainDesktop.Launcher;
 
 internal sealed class CommandContext
 {
+    private static readonly string[] GuiCommands =
+    [
+        "launch",
+        "apply-update",
+        "preview-splash",
+        "preview-error",
+        "preview-update",
+        "preview-oobe",
+        "preview-debug"
+    ];
+
     public string Command { get; }
 
     public string SubCommand { get; }
@@ -28,6 +39,14 @@ internal sealed class CommandContext
         Options.ContainsKey("debug") ||
         System.Diagnostics.Debugger.IsAttached;
 
+    public bool IsPreviewCommand =>
+        Command.StartsWith("preview-", StringComparison.OrdinalIgnoreCase);
+
+    public bool IsGuiCommand =>
+        GuiCommands.Contains(Command, StringComparer.OrdinalIgnoreCase);
+
+    public string? ExplicitAppRoot => GetOption("app-root");
+
     private CommandContext(string command, string subCommand, Dictionary<string, string> options, string[] rawArgs)
     {
         Command = command;