fix(skills): harden rename to managed roots and cover failures

Restrict in-place skill rename to managed skill directories, require
frontmatter name to match before moving, roll back/reject with tests,
hide rename in the UI for unmanaged paths, and drop unused toast keys.

Co-authored-by: Serhii Dziupin <makeittech@users.noreply.github.com>

packages/ui/src/lib/i18n/messages/ko.settings.ts

@@ -685,8 +685,6 @@ export const settingsDict = {
   'settings.skills.sidebar.toast.skillDeleted': '스킬 "{name}"을 삭제했습니다',
   'settings.skills.sidebar.toast.deleteSkillFailed': '스킬을 삭제하지 못했습니다',
   'settings.skills.sidebar.toast.duplicateLoadFailed': '복제를 위한 스킬 세부 정보를 로드하지 못했습니다',
-  'settings.skills.sidebar.toast.renameLoadFailed': '스킬 세부 정보를 로드하지 못했습니다',
-  'settings.skills.sidebar.toast.removeOldAfterRenameFailed': '이름 변경 후 이전 스킬을 제거하지 못했습니다',
   'settings.skills.sidebar.toast.renameFailed': '스킬 이름을 변경하지 못했습니다',
   'settings.skills.sidebar.toast.skillRenamed': '스킬 이름이 "{name}"(으)로 변경되었습니다',
   'settings.skills.sidebar.deleteDialog.title': '스킬 삭제',