Localization / i18n support for CLI UI strings

Summary

Currently the terminal UI chrome (spinner verbs like "Compacting", "Reading", "Thinking"; permission banners like "Bypass permissions"; tool call labels like ⏺ Read, ⏺ Edit) is hardcoded in English. Users who configure the model to respond in another language via CLAUDE.md still see mixed-language output because the CLI chrome doesn't follow.

Motivation

I work primarily in Spanish and Claude Code respects that for model output, but the surrounding UI keeps injecting English words (compacting, bypass, reading, editing, agents, etc.) into an otherwise-Spanish workflow. This is jarring and, for teammates with weaker English, occasionally confusing.

Requested

A --lang / --locale flag or CLAUDE_CODE_LOCALE env var that translates the CLI chrome to at least the languages Claude itself is fluent in (es, pt, fr, de, it, ja, zh, ...).

Code/CLI/API identifiers (tool names, flags, file paths) should stay in English regardless — only human-readable status/label strings need translation.

Environment

• Claude Code CLI
• Windows 11, PowerShell 7 + Git Bash

Thanks!