fix(demo): correct directory rename operation in DemonstrateVFS

Fixes #130

The RenameDirectory method signature takes (VFSDirectoryPath, string),
not (VFSDirectoryPath, VFSDirectoryPath). Updated the demo to use the
correct method signature.

Changes:
- Uncommented the directory rename step
- Fixed second parameter to be a string ('heroes') instead of VFSDirectoryPath
- Removed TODO comment

Tests: All 379 unit tests + 71 GitHub tests pass on net10.0

Author: Ritchie

src/Atypical.VirtualFileSystem.DemoCli/Commands/DemonstrateVFS.cs

@@ -62,9 +62,8 @@ public override int Execute(CommandContext context, CancellationToken cancellati
             () => vfs.MoveDirectory(new VFSDirectoryPath("/heroes"), new VFSDirectoryPath("/avengers")));
 
         // Rename a directory
-        // TODO: fix rename directory
-        // ProcessStep(vfs, "RENAME DIRECTORY",
-        //     () => vfs.RenameDirectory(new VFSDirectoryPath("/avengers"), new VFSDirectoryPath("/heroes")));
+        ProcessStep(vfs, "RENAME DIRECTORY",
+            () => vfs.RenameDirectory(new VFSDirectoryPath("/avengers"), "heroes"));
 
         return 0;
     }