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.Tests/ViewModels/SettingsViewModelOwnershipTests.cs

@@ -30,7 +30,7 @@ public class SettingsViewModelOwnershipTests : IDisposable
         var settingsService = new SettingsService(new SettingsRepository(_tempFile));
         var mockBranding = new Mock<IBrandingService>().Object;
         var logger = NullLogger<FeatureViewModelBase>.Instance;
-        return new SettingsViewModel(settingsService, mockBranding, logger);
+        return new SettingsViewModel(settingsService, mockBranding, new ThemeManager(NullLogger<ThemeManager>.Instance), logger);
     }
 
     [Fact]
@@ -50,7 +50,7 @@ public class SettingsViewModelOwnershipTests : IDisposable
         var settingsService = new SettingsService(new SettingsRepository(_tempFile));
         var mockBranding = new Mock<IBrandingService>().Object;
         var logger = NullLogger<FeatureViewModelBase>.Instance;
-        var vm = new SettingsViewModel(settingsService, mockBranding, logger);
+        var vm = new SettingsViewModel(settingsService, mockBranding, new ThemeManager(NullLogger<ThemeManager>.Instance), logger);
 
         await vm.LoadAsync();
         vm.AutoTakeOwnership = true;