Feature Request: i18n/Localization support for CLI UI strings

Summary

The Claude Code CLI has hardcoded English strings in its UI (React Ink interface) that cannot be customized or translated. While Claude's responses can be configured to use any language via CLAUDE.md, the surrounding UI chrome remains in English, creating an inconsistent experience for non-English speakers.

Examples of hardcoded strings

• "Entered plan mode" / "Exited plan mode"
• "Running X Explore agents…"
• "ctrl+o to expand" / "ctrl+b to run in background"
• "Initializing…"
• "Deep sync flow analysis" / agent status labels
• "tool uses" / "tokens"
• Tool permission prompts ("Allow?", "Yes", "No")

Proposal

Add i18n/localization support for the CLI's UI strings, allowing users to configure the interface language. This could be:

1. A locale setting in ~/.claude/settings.json (e.g., "locale": "pt-BR")
2. A translation file approach (e.g., ~/.claude/i18n/pt-BR.json) for community-contributed translations
3. System locale detection via $LANG / $LC_ALL environment variables

Use case

Users who work primarily in non-English languages (Portuguese, Spanish, French, Japanese, etc.) already configure Claude's responses via CLAUDE.md. Having the CLI UI also respect the user's language would provide a fully localized experience.

Current workaround

There is no workaround — these strings are compiled into the CLI binary and cannot be changed by users.

Environment

• Claude Code CLI (latest)
• macOS / Linux / Windows
• Any non-English locale