[Feature Request] Add Vietnamese (and other languages) UI localization

Feature request: UI localization / language setting

Problem
Claude Code's CLI interface (menus, status line, system messages, slash-command text like /help and /config) is English-only. There is currently no setting or flag to change the interface language. While Claude can be instructed via CLAUDE.md to respond in another language, the UI chrome itself cannot be translated.

Request
Please add a language / locale option (in settings.json or via a flag) to localize the CLI interface. I would like Vietnamese (vi) support.

Why
Non-English-speaking users would find Claude Code much more accessible if the interface matched their language.

Thank you!