Introduce a lightweight useI18n composable (zh default, auto-detect via
navigator.language, manual toggle persisted to localStorage) with full
zh/en dictionaries, and wire translation keys through the console UI.
Add a super-admin-only Groups tab to create, edit and delete groups
(name, admin ids, owner scope). Routes now require a group via a select
in the editor, group names are shown on route cards, and the new
useMe/useGroups composables back the UI.
