Update src/specify_cli/__init__.py

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: mbachorik

src/specify_cli/__init__.py

@@ -2867,6 +2867,11 @@ def extension_update(
                         if extension_dir.exists():
                             shutil.rmtree(extension_dir)
                         shutil.copytree(backup_ext_dir, extension_dir)
+                    else:
+                        # If no backup exists but an extension directory was created
+                        # during the failed update, remove it to fully revert state.
+                        if extension_dir.exists():
+                            shutil.rmtree(extension_dir)
 
                     # Remove any NEW command files created by failed install
                     # (files that weren't in the original backup)