- Add Japanese README (README_ja.md)
- Add Japanese documentation (v0-v4)
- Remove mixed-language tables from all READMEs
- Each language now only references its own content
- Update language switcher links in all READMEs
Supported languages:
- English (README.md, docs/v*-*.md)
- Chinese (README_zh.md, docs/v*-*中文*.md)
- Japanese (README_ja.md, docs/v*-*日本語*.md)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
