Add Git overlay, operation tools, and virtualized preview so large folders stay responsive.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/Explorer.Presentation/RangeObservableCollection.cs

@@ -0,0 +1,43 @@
+using System.Collections.ObjectModel;
+using System.Collections.Specialized;
+using System.ComponentModel;
+
+namespace Explorer.Presentation;
+
+public sealed class RangeObservableCollection<T> : ObservableCollection<T>
+{
+    public void AddRange(IEnumerable<T> items)
+    {
+        ArgumentNullException.ThrowIfNull(items);
+        var list = items as IList<T> ?? items.ToList();
+        if (list.Count == 0)
+        {
+            return;
+        }
+
+        CheckReentrancy();
+        foreach (var item in list)
+        {
+            Items.Add(item);
+        }
+
+        OnPropertyChanged(new PropertyChangedEventArgs(nameof(Count)));
+        OnPropertyChanged(new PropertyChangedEventArgs("Item[]"));
+        OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
+    }
+
+    public void ReplaceAll(IList<T> items)
+    {
+        ArgumentNullException.ThrowIfNull(items);
+        CheckReentrancy();
+        Items.Clear();
+        foreach (var item in items)
+        {
+            Items.Add(item);
+        }
+
+        OnPropertyChanged(new PropertyChangedEventArgs(nameof(Count)));
+        OnPropertyChanged(new PropertyChangedEventArgs("Item[]"));
+        OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
+    }
+}