[FEATURE]:Feature request: i18n / multi-language support for TUI interface #27445

Feature hasn't been suggested before.

• I have verified this feature I'm about to request hasn't been suggested before.

Describe the enhancement you want to request

Currently the TUI interface (menus, buttons, option labels, slash commands) is
English-only. The AI conversation can be guided to reply in other languages via
instructions, but all built-in UI text remains untranslatable.
It would be great to have:

1. A locale config option (e.g., "locale": "zh-CN")
2. Or a plugin hook to intercept/replace UI rendering strings
3. Community-contributed language packs
   This is important for non-English-speaking developers who want a fully native
   experience.