feat(03-07): create StorageView XAML, DI registration, and MainWindow wiring

- StorageView.xaml: DataGrid with IndentLevel-based name indentation
- StorageView.xaml.cs: code-behind wiring DataContext to StorageViewModel
- IndentConverter.cs: IndentConverter, BytesConverter, InverseBoolConverter
- App.xaml: register converters and RightAlignStyle as Application.Resources
- App.xaml.cs: register IStorageService, StorageCsvExportService, StorageHtmlExportService, StorageViewModel, StorageView
- MainWindow.xaml: add x:Name=StorageTabItem to Storage TabItem
- MainWindow.xaml.cs: wire StorageTabItem.Content from DI

SharepointToolbox/Views/Converters/IndentConverter.cs

@@ -0,0 +1,47 @@
+using System.Globalization;
+using System.Windows;
+using System.Windows.Data;
+
+namespace SharepointToolbox.Views.Converters;
+
+/// <summary>Converts IndentLevel (int) to WPF Thickness for DataGrid indent.</summary>
+[ValueConversion(typeof(int), typeof(Thickness))]
+public class IndentConverter : IValueConverter
+{
+    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
+    {
+        int level = value is int i ? i : 0;
+        return new Thickness(level * 16, 0, 0, 0);
+    }
+
+    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+        => throw new NotImplementedException();
+}
+
+/// <summary>Converts byte count (long) to human-readable size string.</summary>
+[ValueConversion(typeof(long), typeof(string))]
+public class BytesConverter : IValueConverter
+{
+    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
+    {
+        long bytes = value is long l ? l : 0L;
+        if (bytes >= 1_073_741_824L) return $"{bytes / 1_073_741_824.0:F2} GB";
+        if (bytes >= 1_048_576L)     return $"{bytes / 1_048_576.0:F2} MB";
+        if (bytes >= 1024L)          return $"{bytes / 1024.0:F2} KB";
+        return $"{bytes} B";
+    }
+
+    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+        => throw new NotImplementedException();
+}
+
+/// <summary>Inverts a bool binding — used to disable controls while an operation is running.</summary>
+[ValueConversion(typeof(bool), typeof(bool))]
+public class InverseBoolConverter : IValueConverter
+{
+    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
+        => value is bool b && !b;
+
+    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+        => value is bool b && !b;
+}