- Reposition admin mobile bar from top-0/z-10 to top-16/z-40 so it
sits below the main Navbar instead of behind it
- Make Sheet controlled so the drawer closes when a nav link is tapped
- Pass onNavigate callback to AdminNavLinks to close Sheet on navigation
https://claude.ai/code/session_01F7rJW6gpaXMiSF3wQYrmhC