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/Themes/DarkPalette.xaml

@@ -0,0 +1,27 @@
+<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
+
+  <!-- Dark palette -->
+  <SolidColorBrush x:Key="AppBgBrush"         Color="#15181F" />
+  <SolidColorBrush x:Key="SurfaceBrush"       Color="#1E2230" />
+  <SolidColorBrush x:Key="SurfaceAltBrush"    Color="#272C3B" />
+  <SolidColorBrush x:Key="SurfaceAltBrushAlt" Color="#222636" />
+  <SolidColorBrush x:Key="BorderSoftBrush"    Color="#323849" />
+  <SolidColorBrush x:Key="BorderStrongBrush"  Color="#3F475B" />
+  <SolidColorBrush x:Key="TextBrush"          Color="#E7EAF1" />
+  <SolidColorBrush x:Key="TextMutedBrush"     Color="#9AA3B2" />
+  <SolidColorBrush x:Key="AccentBrush"        Color="#60A5FA" />
+  <SolidColorBrush x:Key="AccentHoverBrush"   Color="#3B82F6" />
+  <SolidColorBrush x:Key="AccentPressedBrush" Color="#2563EB" />
+  <SolidColorBrush x:Key="AccentSoftBrush"    Color="#1E3A5F" />
+  <SolidColorBrush x:Key="AccentForegroundBrush" Color="#0B1220" />
+  <SolidColorBrush x:Key="DangerBrush"        Color="#F87171" />
+  <SolidColorBrush x:Key="SuccessBrush"       Color="#34D399" />
+  <!-- Forced-dark text for elements painted with hardcoded light pastel backgrounds (risk tiles, colored rows). -->
+  <SolidColorBrush x:Key="OnColoredBgBrush"   Color="#1F2430" />
+  <SolidColorBrush x:Key="SelectionBrush"     Color="#2A4572" />
+  <SolidColorBrush x:Key="ScrollThumbBrush"   Color="#4A5366" />
+  <SolidColorBrush x:Key="TooltipBgBrush"     Color="#0B1220" />
+  <SolidColorBrush x:Key="TooltipFgBrush"     Color="#E7EAF1" />
+
+</ResourceDictionary>