fix: Remove Traefik labels and add Nginx Proxy Manager support

- Remove Traefik-specific labels (user uses Nginx Proxy Manager)
- Add proper host header handling in middleware for 421 fix
- Create NGINX_PROXY_MANAGER_SETUP.md with complete setup guide
- Fix 421 Misdirected Request by ensuring proper proxy headers

middleware.ts

@@ -5,8 +5,18 @@ export function middleware(request: NextRequest) {
   // For /manage and /editor routes, the pages handle their own authentication
   // No middleware redirect needed - let the pages show login forms
 
+  // Fix for 421 Misdirected Request with Nginx Proxy Manager
+  // Ensure proper host header handling for reverse proxy
+  const hostname = request.headers.get('host') || request.headers.get('x-forwarded-host') || '';
+  
   // Add security headers to all responses
   const response = NextResponse.next();
+  
+  // Set proper headers for Nginx Proxy Manager
+  if (hostname) {
+    response.headers.set('X-Forwarded-Host', hostname);
+    response.headers.set('X-Real-IP', request.headers.get('x-real-ip') || request.headers.get('x-forwarded-for') || '');
+  }
 
   // Security headers (complementing next.config.ts headers)
   response.headers.set("X-DNS-Prefetch-Control", "on");