Add multi-language support (ru-RU, ja-JP, ko-KR, etc.)

[potap3789-ai]

ZCode currently only supports zh-CN and en-US. Please add more languages: Russian (ru-RU), Japanese (ja-JP), Korean (ko-KR), and others.

The app already uses react-intl with formatMessage, so the i18n architecture is in place — it just needs additional locale dictionaries.

Russian is spoken by ~260 million people. This would significantly grow your user base.

Thank you!