[Feature] Internationalization (i18n) / localization of the CLI interface

Summary

The language setting (e.g. "language": "french") only controls the language of the model's responses. The Claude Code interface itself remains English-only: menus, permission prompts, the status line, help text, confirmation dialogs (→ Confirm?), error messages, etc.

There is currently no setting, /config option, or outputStyle that localizes the UI chrome.

Why this matters

For non-English-speaking users and teams, Claude Code is a mixed-language experience: the assistant answers in the user's language, but the tool's own interface stays in English. This:

• creates friction and a steeper learning curve for non-English speakers,
• is inconsistent (the product clearly supports a language preference, but applies it only partially),
• is a barrier to adoption in non-English organizations and regulated/public-sector contexts where UI language can be a requirement.

Current behavior

• settings.json → "language": "french" → model responses are in French ✅
• CLI interface (menus, prompts, status line, help, dialogs) → English only ❌

Requested behavior

Have the existing language setting also localize the CLI interface strings (i18n of the UI chrome), or introduce a dedicated setting if separation is preferred. Even community-contributed translation files would be a great start.

Environment

• Claude Code CLI
• Platform: Linux
• Locale: fr_FR