feat: adicionar página de Monitorização

- React Router para SPA routing
- Página /monitor com status de sistemas
- Cards de servidores, serviços, sites, containers
- Barras de progresso animadas
- Auto-refresh de 60s
- Link no header do dashboard

DeskCRM Task: #1604

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/App.tsx

@@ -493,7 +493,7 @@ function App() {
                   <LayoutDashboard className="w-4 h-4" />
                   Dashboard
                 </a>
-                <a href="/monitor.php" className="px-4 py-2 rounded-lg text-zinc-400 hover:text-white hover:bg-white/10 text-sm font-medium transition-all flex items-center gap-2">
+                <a href="/monitor" className="px-4 py-2 rounded-lg text-zinc-400 hover:text-white hover:bg-white/10 text-sm font-medium transition-all flex items-center gap-2">
                   <Activity className="w-4 h-4" />
                   Monitor
                 </a>