Remove unused CSS and i18n strings
See:
- https://github.com/ivanblazevic/ngx-unused-css
- https://dev.to/dylanvdmerwe/reduce-angular-style-size-using-purgecss-to-remove-unused-styles-3b2k
- https://www.youtube.com/watch?v=1rwRovyQGuo
- i18n: https://github.com/FranciscoKnebel/ngx-translate-check#readme
- i18n: https://freesoft.dev/program/136441562