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/hooks/useOnClickOutside.ts

@@ -0,0 +1,24 @@
+import { useEffect, type RefObject } from 'react';
+
+export function useOnClickOutside<T extends HTMLElement = HTMLElement>(
+  ref: RefObject<T | null>,
+  handler: () => void
+) {
+  useEffect(() => {
+    const listener = (event: MouseEvent | TouchEvent) => {
+      // Do nothing if clicking ref's element or descendent elements
+      if (!ref.current || ref.current.contains(event.target as Node)) {
+        return;
+      }
+      handler();
+    };
+
+    document.addEventListener('mousedown', listener);
+    document.addEventListener('touchstart', listener);
+
+    return () => {
+      document.removeEventListener('mousedown', listener);
+      document.removeEventListener('touchstart', listener);
+    };
+  }, [ref, handler]);
+}