Add complete README translations for:
- German (README-de.md)
- French (README-fr.md)
- Greek (README-el.md)
- Japanese (README-ja.md)
- Italian (README-it.md)
- Korean (README-ko.md)
- Indonesian (README-id.md)
Update all README files with language switcher links to all 10 languages.
Add target languages comment to track supported translations.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
