RenameYamlKey can only rename a key in place, under the same parent. To
migrate a keybinding from one section to another we need to relocate the
key to a different parent mapping, which is a move, not a rename.
MoveYamlKey creates intermediate maps at the destination as needed and
prunes any maps left empty behind the key, so a section that held only
the moved key doesn't linger as an empty mapping in the user's config.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>