Feature Request: German (Deutsch) language pack for the CLI UI

Is your feature request related to a problem? Please describe.
The Claude Code CLI interface (menus, /help text, status line, tool/error messages, etc.) is currently only available in English. There is no way to switch the tool's own UI to another language via settings.json or any other configuration option (checked ~/.claude/settings.json and the global config — no locale field exists).

Describe the solution you'd like
A German language pack / locale setting for the CLI UI itself (separate from the model's conversational language, which can already be steered via instructions). E.g. a "locale": "de" option in settings.json that localizes menus, help text, and system messages.

Describe alternatives you've considered
Currently just asking the model to respond in German in chat — that works for conversational output, but the surrounding CLI chrome (menus, keybindings help, etc.) stays English.

Additional context
Reported on behalf of a user running Claude Code on a Raspberry Pi 5 who would like a fully German-language experience.