Add settings, cloud places, and optional archive-content indexing.

Keep official clients in charge of sync while Explorer can group locations, persist UI prefs, and list zip/rar/7z members without extracting them.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/Explorer.App/SettingsWindow.xaml.cs

@@ -0,0 +1,51 @@
+using System.Windows;
+using Explorer.Application;
+using Explorer.Presentation.ViewModels;
+
+namespace Explorer.App;
+
+public partial class SettingsWindow : Window
+{
+    private readonly MainViewModel _vm;
+    private readonly string _originalTheme;
+
+    public SettingsWindow(MainViewModel vm)
+    {
+        InitializeComponent();
+        _vm = vm;
+        var prefs = vm.CurrentPreferences();
+        _originalTheme = prefs.Theme;
+        ThemeDark.IsChecked = prefs.Theme != "Light";
+        ThemeLight.IsChecked = prefs.Theme == "Light";
+        GroupNetwork.IsChecked = prefs.GroupNetworkPlaces;
+        GroupCloud.IsChecked = prefs.GroupCloudPlaces;
+        IndexArchives.IsChecked = prefs.IndexArchiveContents;
+    }
+
+    private void OnThemeChanged(object sender, RoutedEventArgs e)
+    {
+        if (!IsLoaded)
+        {
+            return;
+        }
+
+        _vm.Theme = ThemeLight.IsChecked == true ? "Light" : "Dark";
+    }
+
+    private async void OnOk(object sender, RoutedEventArgs e)
+    {
+        var prefs = new UiPreferences(
+            ThemeLight.IsChecked == true ? "Light" : "Dark",
+            GroupNetwork.IsChecked == true,
+            GroupCloud.IsChecked == true,
+            IndexArchives.IsChecked == true);
+        await _vm.ApplyPreferencesAsync(prefs).ConfigureAwait(true);
+        DialogResult = true;
+        Close();
+    }
+
+    private void OnCancel(object sender, RoutedEventArgs e)
+    {
+        _vm.Theme = _originalTheme;
+    }
+}