refactor: streamline README and move translations to separate file

- Reduce README from 1293 to 170 lines (~87% smaller)
- Organize concepts into 7 categories with descriptions
- Link all concepts to 33jsconcepts.com documentation site
- Remove inline articles/videos (now available on docs site)
- Create TRANSLATIONS.md with all 42 community translations
- Keep original header image and GitHub recognition badge

Author: leonardomso