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/Views/Common/Spinner.xaml

@@ -0,0 +1,26 @@
+<UserControl x:Class="SharepointToolbox.Views.Common.Spinner"
+             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             Width="20" Height="20">
+    <Grid RenderTransformOrigin="0.5,0.5">
+        <Grid.RenderTransform>
+            <RotateTransform x:Name="Rot" Angle="0" />
+        </Grid.RenderTransform>
+        <Grid.Triggers>
+            <EventTrigger RoutedEvent="Loaded">
+                <BeginStoryboard>
+                    <Storyboard>
+                        <DoubleAnimation
+                            Storyboard.TargetName="Rot"
+                            Storyboard.TargetProperty="Angle"
+                            From="0" To="360" Duration="0:0:1"
+                            RepeatBehavior="Forever" />
+                    </Storyboard>
+                </BeginStoryboard>
+            </EventTrigger>
+        </Grid.Triggers>
+        <Ellipse Stroke="{DynamicResource BorderSoftBrush}" StrokeThickness="3" />
+        <Ellipse Stroke="{DynamicResource AccentBrush}" StrokeThickness="3"
+                 StrokeDashArray="3 3" StrokeDashCap="Round" />
+    </Grid>
+</UserControl>