Compiles custom SCSS that sources Bootstrap's own SCSS — overriding variables
to theme it — vendored from npm and served by web-modules. No Node, no dart-sass.
cargo run -p bootstrap-scss
# open http://127.0.0.1:8080/web/app.scssoverrides$primary/$secondary/… then@imports Bootstrap'sscss/bootstrap. web-modules keeps packages'.scsssources, so grass can build Bootstrap from source and apply the overrides →/app.css, on the fly.
web/web_modules/ is generated.