fix(build): compile the entry points, not the whole scss tree

[mrholek]

dist/css had six folders in it that nobody asked for.

What happened

css-compile ran in directory mode:

sass --style expanded --source-map --embed-sources --no-error-css scss/:dist/css/

which compiles every file in the tree that is not a partial. The v6 reorganisation added barrel files — scss/{buttons,content,forms,helpers,layout,mixins}/index.scss, pure @forward aggregators — and because they have no leading underscore, each became an entry point and emitted a stylesheet of its own.

The result, per build:

folder	index.css
forms/	66 956 B — a second copy of the whole forms layer
buttons/	41 183 B
content/	19 127 B
layout/	19 144 B
helpers/	11 204 B
mixins/	39 B — mixins emit no CSS

24 files with their minified variants and source maps, roughly 157 kB before minification. They were not gitignored, and files ships dist/{css,js}/**/*.{css,js,map} — so they were headed for the published package, source maps and all (and --embed-sources puts the full Sass into those).

The fix

Name the five real entry points, which is exactly what upstream Bootstrap does — their css-compile lists bootstrap.scss, bootstrap-grid.scss, bootstrap-reboot.scss and bootstrap-utilities.scss, and their scss/forms/index.scss and scss/helpers/index.scss barrels are spelled the same way ours are. Directory mode was the difference, not the file naming — worth keeping in mind, since renaming the barrels to _index.scss would have diverged from a structure we deliberately track.

Verification

Compiled the same tree both ways and diffed:

IDENTYCZNY  coreui.css
IDENTYCZNY  coreui-grid.css
IDENTYCZNY  coreui-reboot.css
IDENTYCZNY  coreui-utilities.css
IDENTYCZNY  themes/bootstrap/bootstrap.css

Byte-identical, all five. The only difference in the output tree is the six barrels that stop being written.

Plus stylelint, bundlewatch and the local pre-push gate (lint → dist → typecheck → sass suite → class API → bundlewatch → js tests).

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