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

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

tests/Explorer.FileOperations.Tests/FileOperationTests.cs

@@ -44,4 +44,5 @@ file sealed class StubShell : IShellFileOperations
     { error = "n/a"; return false; }
     public bool CreateShortcut(string targetPath, string shortcutPath, out string? error)
     { error = null; return true; }
+    public bool EmptyRecycleBin(out string? error) { error = null; return true; }
 }