- AdminLayout now uses flex-row: AdminSidebar (left) + main (right)
- Removed NavBar import and max-w-5xl centered constraint
- Main content area takes remaining width with px-8 py-8 padding
- src/lib/admin-queries.ts: getAllClientsWithPayments() and getClientById() for admin DB reads
- src/components/admin/NavBar.tsx: minimal nav with Clienti link and Esci (logout) button
- src/app/admin/layout.tsx: wraps all /admin/* pages with NavBar + centered main content area