* BREAKING CHANGE: refactor with Dart Sass (supplement to #741)
* chore: update .gitignore to include .vercel and .env*.local
* CI: add build script for Hugo site deployment on Vercel
* CI: update build script for Hugo site deployment on Vercel
* refactor: update SCSS layout styles and introduce page-style mixin
* refactor: reorganize SCSS files and improve layout structure
* refactor: rename copy button classes and update related styles