Fix PageSpeed Score on Nginx

PageSpeed penalizes large uncompressed text, short cache lifetimes on static files, and slow server response. Nginx can enable gzip or a brotli module, HTTP/2, and sendfile tuning without changing application code.

Preconnect and preload hints sometimes belong in upstream HTML, but Nginx can inject Link headers for critical LCP resources. Measure after each change—some optimizations trade CPU for bytes.