server {
  listen 80;
  server_name _;
  root /usr/share/nginx/html;
  index index.html;

  # Hash-versionierte Assets — langer Cache OK
  location /assets/ {
    expires 1y;
    add_header Cache-Control "public, immutable";
    try_files $uri =404;
  }

  # SPA-Fallback: unbekannte Pfade → index.html (React-Routing-kompatibel)
  location / {
    add_header Cache-Control "no-cache, no-store, must-revalidate";
    try_files $uri /index.html;
  }

  add_header X-Content-Type-Options "nosniff" always;
  add_header X-Frame-Options "SAMEORIGIN" always;
  add_header Referrer-Policy "strict-origin-when-cross-origin" always;
}