Implement complete frontend with admin panel and theme system

- Add admin authentication and dashboard
- Create event management pages (list, create, edit, archive)
- Implement gallery enhancements (search, sorting, bulk download)
- Add email configuration and archive management pages
- Integrate Umami analytics with tracking throughout the app
- Add comprehensive error boundaries and loading states
- Implement accessibility features (WCAG 2.1 AA compliance)
- Create theme system with preset themes and customization
- Add branding settings and company information management
- Fix backend database initialization and health check
- Configure proper API URLs and environment variables

🤖 Generated with [Claude Code](https://claude.ai/code)

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

frontend/src/components/admin/AdminLayout.tsx

@@ -0,0 +1,41 @@
+import React, { useState } from 'react';
+import { Outlet, Navigate } from 'react-router-dom';
+
+import { useAdminAuth } from '../../contexts';
+import { AdminSidebar } from './AdminSidebar';
+import { AdminHeader } from './AdminHeader';
+
+export const AdminLayout: React.FC = () => {
+  const { isAuthenticated } = useAdminAuth();
+  const [sidebarOpen, setSidebarOpen] = useState(false);
+
+  if (!isAuthenticated) {
+    return <Navigate to="/admin/login" replace />;
+  }
+
+  return (
+    <div className="min-h-screen bg-neutral-50">
+      {/* Mobile sidebar backdrop */}
+      {sidebarOpen && (
+        <div
+          className="fixed inset-0 bg-black bg-opacity-50 z-40 lg:hidden"
+          onClick={() => setSidebarOpen(false)}
+        />
+      )}
+
+      {/* Sidebar */}
+      <AdminSidebar isOpen={sidebarOpen} onClose={() => setSidebarOpen(false)} />
+
+      {/* Main content */}
+      <div className="lg:pl-64">
+        {/* Header */}
+        <AdminHeader onMenuClick={() => setSidebarOpen(true)} />
+
+        {/* Page content */}
+        <main id="main-content" className="px-4 sm:px-6 lg:px-8 py-8">
+          <Outlet />
+        </main>
+      </div>
+    </div>
+  );
+};