chore: release v2.4

- Add theme system (Dark/Light palettes, ModernTheme, ThemeManager)
- Add InputDialog, Spinner common view
- Add DuplicatesCsvExportService
- Refresh views, dialogs, and view models across tabs
- Update localization strings (en/fr)
- Tweak services (transfer, permissions, search, user access, ownership elevation, bulk operations)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

SharepointToolbox/MainWindow.xaml

@@ -8,6 +8,9 @@
         xmlns:views="clr-namespace:SharepointToolbox.Views.Tabs"
         mc:Ignorable="d"
         Title="{Binding Source={x:Static loc:TranslationSource.Instance}, Path=[app.title]}"
+        Background="{DynamicResource AppBgBrush}"
+        Foreground="{DynamicResource TextBrush}"
+        TextOptions.TextFormattingMode="Ideal"
         MinWidth="900" MinHeight="600" Height="700" Width="1100">
   <DockPanel>
     <!-- Toolbar -->
@@ -28,7 +31,7 @@
               ToolTip="{Binding Source={x:Static loc:TranslationSource.Instance}, Path=[toolbar.selectSites.tooltip]}" />
       <TextBlock Text="{Binding GlobalSitesSelectedLabel}"
                  VerticalAlignment="Center" Margin="6,0,0,0"
-                 Foreground="Gray" />
+                 Foreground="{DynamicResource TextMutedBrush}" />
     </ToolBar>
 
     <!-- StatusBar: tenant name | operation status text | progress % -->