[CLI] `build-scss` requires `dist` directory exists, still runs after showing error

If you don't have a dist directory and run build-scss, you'll see an error

✖ Failed to build stylesheets for Core: ENOENT: no such file or directory, open './dist/core.css'

but it will continue to run anyways (and can't be interrupted )

brand-openedx has a line in the Makefile working around this

.PHONY: build
build:
	rm -rf dist && mkdir dist
	npm run build-tokens
	npm run build-scss

We should either stop trying to build if we don't have an output directory, or create one if it is missing.

Start by locating the implementation behind the build-scss command and run it without a dist directory to reproduce the ENOENT error and continued execution. Decide whether the command should create the missing output directory or stop cleanly, then verify that the chosen behavior completes without the reported error.