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/App.xaml.cs

@@ -50,6 +50,18 @@ public partial class App : Application
         App app = new();
         app.InitializeComponent();
 
+        // Apply persisted theme (System/Light/Dark) before MainWindow constructs so brushes resolve correctly.
+        try
+        {
+            var theme = host.Services.GetRequiredService<ThemeManager>();
+            var settings = host.Services.GetRequiredService<SettingsService>().GetSettingsAsync().GetAwaiter().GetResult();
+            theme.ApplyFromString(settings.Theme);
+        }
+        catch (Exception ex)
+        {
+            Log.Warning(ex, "Failed to apply persisted theme at startup");
+        }
+
         var mainWindow = host.Services.GetRequiredService<MainWindow>();
 
         // Wire LogPanelSink now that we have the RichTextBox
@@ -101,6 +113,7 @@ public partial class App : Application
         services.AddSingleton<ISessionManager>(sp => sp.GetRequiredService<SessionManager>());
         services.AddSingleton<ProfileService>();
         services.AddSingleton<SettingsService>();
+        services.AddSingleton<ThemeManager>();
         services.AddSingleton<MainWindowViewModel>();
         // Phase 11-04: ProfileManagementViewModel and SettingsViewModel now receive IBrandingService and GraphClientFactory
         services.AddTransient<ProfileManagementViewModel>();
@@ -125,6 +138,7 @@ public partial class App : Application
         // Phase 3: Duplicates
         services.AddTransient<IDuplicatesService, DuplicatesService>();
         services.AddTransient<DuplicatesHtmlExportService>();
+        services.AddTransient<DuplicatesCsvExportService>();
         services.AddTransient<DuplicatesViewModel>();
         services.AddTransient<DuplicatesView>();