Make cacheable sidebar cache keys aware of menu and locale context #25
Description
Problem
The cacheable sidebar stores rendered sidebar blocks in a single session key: admin_sidebar_cache_for_user.
That means different admin menus, themes, or locales can reuse stale sidebar data inside the same session.
Impact
- menu changes may not appear immediately
- translated labels can stay in the previous locale
- different sidebar configurations can collide in the same user session
Expected behavior
Cache entries should be scoped to the relevant menu context, at least by menu definition and locale, or the template should avoid caching fully translated output in a single shared session key.