Add OOBE startup presentation and settings merge

Introduce a new OOBE step for "Startup & Presentation" that exposes startup and UI preferences in OobeWindow (toggles for taskbar, slide/fade transitions, fused popup, and autostart). Add HostAppSettingsOobeMerger to read/write Host settings.json (PascalCase fields) and MergeStartupPresentation behavior, plus LauncherWindowsStartupService to sync the current Launcher into the Windows Run key on Windows. Wire UI handlers, persist choices on Next, and load defaults when entering the step. Include unit tests for the merger, adjust SettingsWindow navigation pane/toggle handling, and update docs/LAUNCHER.md to describe the new OOBE step and implementation files.

LanMountainDesktop/Views/SettingsWindow.axaml

@@ -78,7 +78,9 @@
                              OpenPaneLength="283"
                              IsSettingsVisible="False"
                              IsBackButtonVisible="False"
-                             SelectionChanged="OnNavigationSelectionChanged">
+                             IsPaneToggleButtonVisible="False"
+                             SelectionChanged="OnNavigationSelectionChanged"
+                             ItemInvoked="OnNavigationItemInvoked">
             <ui:FANavigationView.Styles>
                 <Style Selector="ui|FANavigationView#RootNavigationView:minimal">
                     <Setter Property="IsPaneToggleButtonVisible" Value="False" />
@@ -178,20 +180,6 @@
                                        Foreground="{DynamicResource TextFillColorPrimaryBrush}" />
                     </Button>
 
-                    <Button x:Name="TitleBarPaneToggleButton"
-                            Classes="titlebar-icon-button"
-                            Width="48"
-                            Height="48"
-                            Margin="0,-8,-8,-8"
-                            ToolTip.Tip="{Binding TogglePaneTooltip}"
-                            Click="OnTitleBarPaneToggleClick">
-                        <fi:FluentIcon x:Name="TitleBarPaneToggleButtonIcon"
-                                       Icon="Navigation"
-                                       IconVariant="Regular"
-                                       FontSize="16"
-                                       Foreground="{DynamicResource TextFillColorPrimaryBrush}" />
-                    </Button>
-
                     <fi:FluentIcon x:Name="WindowBrandIcon"
                                    Icon="Settings"
                                    IconVariant="Filled"

LanMountainDesktop/Views/SettingsWindow.axaml.cs

@@ -31,6 +31,7 @@ public partial class SettingsWindow : FAAppWindow, ISettingsPageHostContext
     private const double MinPaneOpenLength = 260d;
     private const double MaxPaneOpenLength = 288d;
     private const double BaseNarrowThreshold = 800d;
+    private const string PaneToggleItemTag = "__pane_toggle__";
 
     private readonly ISettingsPageRegistry _pageRegistry;
     private readonly IHostApplicationLifecycle _hostApplicationLifecycle;
@@ -42,6 +43,7 @@ public partial class SettingsWindow : FAAppWindow, ISettingsPageHostContext
     private bool _isResponsiveRefreshPending;
     private bool _isRestartPromptVisible;
     private bool _isHandlingSearchSelection;
+    private FANavigationViewItem? _paneToggleItem;
     private Border? _currentSearchHighlight;
     private Action? _searchHighlightCleanup;
 
@@ -96,7 +98,6 @@ public partial class SettingsWindow : FAAppWindow, ISettingsPageHostContext
         SyncTitleText();
         UpdateChromeMetrics();
         UpdatePaneToggleVisibility();
-        UpdatePaneToggleIcon();
         UpdateResponsiveLayout();
         RequestResponsiveLayoutRefresh();
     }
@@ -216,6 +217,16 @@ public partial class SettingsWindow : FAAppWindow, ISettingsPageHostContext
         RootNavigationView.MenuItems.Clear();
         RootNavigationView.FooterMenuItems.Clear();
 
+        _paneToggleItem = new FANavigationViewItem
+        {
+            Content = string.Empty,
+            Tag = PaneToggleItemTag,
+            IconSource = CreateSettingsIconSource(Symbol.Navigation),
+            SelectsOnInvoked = false
+        };
+        ToolTip.SetTip(_paneToggleItem, ViewModel.TogglePaneTooltip);
+        RootNavigationView.MenuItems.Add(_paneToggleItem);
+
         SettingsPageCategory? previousCategory = null;
 
         foreach (var page in ViewModel.Pages)
@@ -248,10 +259,29 @@ public partial class SettingsWindow : FAAppWindow, ISettingsPageHostContext
     private void OnNavigationSelectionChanged(object? sender, FANavigationViewSelectionChangedEventArgs e)
     {
         _ = sender;
-        var selectedItem = e.SelectedItemContainer ?? e.SelectedItem as FANavigationViewItem;
+        var selectedItem = e.SelectedItemContainer ?? e.SelectedItem as Control;
+        if (IsPaneToggleItem(selectedItem))
+        {
+            RestoreCurrentNavigationSelection();
+            return;
+        }
+
         NavigateTo(selectedItem?.Tag as string, addHistory: true, source: "navigation");
     }
 
+    private void OnNavigationItemInvoked(object? sender, FANavigationViewItemInvokedEventArgs e)
+    {
+        _ = sender;
+        var invokedItem = e.InvokedItemContainer ?? e.InvokedItem as Control;
+        if (!IsPaneToggleItem(invokedItem))
+        {
+            return;
+        }
+
+        ToggleNavigationPane();
+        RestoreCurrentNavigationSelection();
+    }
+
     private void NavigateTo(
         string? pageId,
         bool addHistory,
@@ -803,17 +833,14 @@ public partial class SettingsWindow : FAAppWindow, ISettingsPageHostContext
         return false;
     }
 
-    private void OnTitleBarPaneToggleClick(object? sender, Avalonia.Interactivity.RoutedEventArgs e)
+    private void ToggleNavigationPane()
     {
-        _ = sender;
-        _ = e;
         if (RootNavigationView is null)
         {
             return;
         }
 
         RootNavigationView.IsPaneOpen = !RootNavigationView.IsPaneOpen;
-        UpdatePaneToggleIcon();
         UpdateResponsiveLayout();
         RequestResponsiveLayoutRefresh();
     }
@@ -832,23 +859,35 @@ public partial class SettingsWindow : FAAppWindow, ISettingsPageHostContext
                 UpdatePaneToggleVisibility();
             }
 
-            UpdatePaneToggleIcon();
             RequestResponsiveLayoutRefresh();
         }
     }
 
     /// <summary>
-    /// 仅在 <c>:minimal</c>（<see cref="FANavigationView.IsPaneToggleButtonVisible"/> 为 false）时显示侧栏底部备胎按钮。
-    /// 根 DataContext 为 ViewModel 时，对 <c>#RootNavigationView</c> 的绑定易失效，故用代码同步可见性。
+    /// The NavigationView template toggle is disabled; the first menu item is the only pane toggle.
     /// </summary>
     private void UpdatePaneToggleVisibility()
     {
-        if (TitleBarPaneToggleButton is null || RootNavigationView is null)
+        if (_paneToggleItem is null)
         {
             return;
         }
 
-        TitleBarPaneToggleButton.IsVisible = !RootNavigationView.IsPaneToggleButtonVisible;
+        _paneToggleItem.IsVisible = true;
+        ToolTip.SetTip(_paneToggleItem, ViewModel.TogglePaneTooltip);
+    }
+
+    private static bool IsPaneToggleItem(Control? item)
+    {
+        return string.Equals(item?.Tag as string, PaneToggleItemTag, StringComparison.Ordinal);
+    }
+
+    private void RestoreCurrentNavigationSelection()
+    {
+        if (!string.IsNullOrWhiteSpace(ViewModel.CurrentPageId))
+        {
+            TrySelectNavigationItem(ViewModel.CurrentPageId);
+        }
     }
 
     private void RequestResponsiveLayoutRefresh()
@@ -880,18 +919,6 @@ public partial class SettingsWindow : FAAppWindow, ISettingsPageHostContext
             : compactPaneWidth;
     }
 
-    private void UpdatePaneToggleIcon()
-    {
-        if (TitleBarPaneToggleButtonIcon is null || RootNavigationView is null)
-        {
-            return;
-        }
-
-        TitleBarPaneToggleButtonIcon.Icon = RootNavigationView.IsPaneOpen
-            ? FluentIcons.Common.Icon.LineHorizontal3
-            : FluentIcons.Common.Icon.Navigation;
-    }
-
     private void UpdateChromeMetrics()
     {
         if (_useSystemChrome)