feat(04-02): admin projects list + client detail project cards

- NavBar: add Progetti (/admin/projects) and Impostazioni links
- ProjectRow: project table row with €/h calc (accepted_total / tracked hours)
- /admin/projects: table listing all projects with value, payments, timer, €/h
- /admin/projects/new: create form with client select + ?client_id pre-selection
- project-actions: createProject, archiveProject, unarchiveProject, updateProjectAcceptedTotal
- /admin/clients/[id]: rewritten to show project cards grid instead of tabbed workspace
- getAllClientsWithPayments: add projectBrands[] and ltv (sum of project accepted_totals)
- ClientRow: show project brand names under client name, LTV column replaces Totale

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/app/admin/page.tsx

@@ -48,7 +48,7 @@ export default async function AdminDashboard({
             <thead className="bg-[#f9f9f9] border-b border-[#e5e7eb]">
               <tr>
                 <th className="text-left py-3 px-4 font-medium text-[#71717a]">Cliente</th>
-                <th className="text-left py-3 px-4 font-medium text-[#71717a]">Totale</th>
+                <th className="text-left py-3 px-4 font-medium text-[#71717a]">LTV</th>
                 <th className="text-left py-3 px-4 font-medium text-[#71717a]">Acconto</th>
                 <th className="text-left py-3 px-4 font-medium text-[#71717a]">Saldo</th>
                 <th className="text-left py-3 px-4 font-medium text-[#71717a]">Timer</th>