feat(layout): add admin panel layout with sidebar and header

- Add Sidebar component with navigation items (dashboard, bookings, tournaments, pos, clients, memberships, reports, settings)
- Add Header component with SiteSwitcher and user info/logout
- Add SiteSwitcher component for SUPER_ADMIN multi-site selection
- Add admin layout wrapper with AuthProvider
- Add placeholder Dashboard page

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

apps/web/components/layout/sidebar.tsx

@@ -0,0 +1,74 @@
+'use client';
+
+import Link from 'next/link';
+import { usePathname } from 'next/navigation';
+import {
+  LayoutDashboard,
+  Calendar,
+  Trophy,
+  ShoppingCart,
+  Users,
+  CreditCard,
+  BarChart3,
+  Settings,
+} from 'lucide-react';
+import { cn } from '@/lib/utils';
+
+interface NavItem {
+  label: string;
+  href: string;
+  icon: React.ComponentType<{ className?: string }>;
+}
+
+const navItems: NavItem[] = [
+  { label: 'Dashboard', href: '/admin/dashboard', icon: LayoutDashboard },
+  { label: 'Reservas', href: '/admin/bookings', icon: Calendar },
+  { label: 'Torneos', href: '/admin/tournaments', icon: Trophy },
+  { label: 'Ventas', href: '/admin/pos', icon: ShoppingCart },
+  { label: 'Clientes', href: '/admin/clients', icon: Users },
+  { label: 'Membresías', href: '/admin/memberships', icon: CreditCard },
+  { label: 'Reportes', href: '/admin/reports', icon: BarChart3 },
+  { label: 'Configuración', href: '/admin/settings', icon: Settings },
+];
+
+export function Sidebar() {
+  const pathname = usePathname();
+
+  return (
+    <aside className="fixed left-0 top-0 z-40 h-screen w-64 border-r border-primary-200 bg-white">
+      {/* Logo Section */}
+      <div className="flex h-16 items-center gap-3 border-b border-primary-200 px-6">
+        <div className="flex h-10 w-10 items-center justify-center rounded-lg bg-primary text-white font-bold text-lg">
+          P
+        </div>
+        <span className="text-xl font-semibold text-primary-800">Padel Pro</span>
+      </div>
+
+      {/* Navigation */}
+      <nav className="flex flex-col gap-1 p-4">
+        {navItems.map((item) => {
+          const isActive = pathname === item.href || pathname.startsWith(`${item.href}/`);
+          const Icon = item.icon;
+
+          return (
+            <Link
+              key={item.href}
+              href={item.href}
+              className={cn(
+                'flex items-center gap-3 rounded-lg px-3 py-2.5 text-sm font-medium transition-colors',
+                isActive
+                  ? 'bg-primary text-white'
+                  : 'text-primary-600 hover:bg-primary-50 hover:text-primary-800'
+              )}
+            >
+              <Icon className="h-5 w-5" />
+              {item.label}
+            </Link>
+          );
+        })}
+      </nav>
+    </aside>
+  );
+}
+
+export default Sidebar;