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

    # SPA: cualquier ruta desconocida sirve index.html (React Router).
    location / {
        try_files $uri $uri/ /index.html;
    }

    # Cache de assets con hash.
    location /assets/ {
        expires 1y;
        add_header Cache-Control "public, immutable";
    }

    gzip on;
    gzip_types text/css application/javascript application/json image/svg+xml;
    gzip_min_length 1024;
}