What

Add ngx_brotli to the ISPmanager Nginx build as a dynamic module, and expose a Brotli compression toggle in the website settings UI alongside the existing Gzip option.

Why

Brotli (RFC 7932) is now the standard compression algorithm for the web — supported by 96%+ of browsers and recommended by Google Lighthouse. Compared to gzip, it delivers:

• 20–26% better compression on HTML
• 15–25% better compression on CSS and JavaScript
• Comparable CPU usage at levels 4–6

Not having Brotli available is a measurable handicap for any site hosted on ISPmanager, directly affecting PageSpeed scores and bandwidth costs.

Requested changes

1. Build: include --add-dynamic-module=ngx_brotli in the Nginx configure arguments, shipping ngx_http_brotli_filter_module.so and ngx_http_brotli_static_module.so.
2. Panel UI: add a Brotli toggle in the website optimization settings, generating the following in the vhost configuration:

brotli on;
brotli_comp_level 6;
brotli_static on;
brotli_types text/plain text/css text/javascript application/javascript
            application/json application/xml image/svg+xml font/woff2;

This follows the exact same pattern as the existing Gzip UI control and the template engine mechanism already documented in the ISPmanager developer guide.

ngx_brotli is a stable Google project, widely deployed, and has no known conflicts with any module currently included in the ISPmanager build (ModSecurity, PageSpeed, Lua, HTTP/3).