- add optional `permission` field to nav items in registry
- filter nav items by user permissions in `buildNavigationSections`
- auto-hide sections when all their items are filtered out
- fetch user permissions in `AdminLayout.server.js` and pass to navigation builder
- update docs and README to document `permission` param and new signature
- add `ZEN_DEVKIT` env variable to enable/disable devkit
- add `isDevkitEnabled()` utility and export it from public api
- register devkit nav section and items conditionally when devkit is enabled
- add devkit route handling in admin page client and server
- add DevkitPage, ComponentsPage, and IconsPage client components
BREAKING CHANGE: sup config now derives entries from package.json#exports and a server/client glob instead of manual lists; module structure follows flat + barrel convention with .server.js/.client.js runtime suffixes
hykocx