Add Chinese (Simplified) localization support

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

Hello Claude Code team,

I would like to request adding Chinese (Simplified) localization support for the Claude Code extension UI.

Proposed Solution

Add Chinese (Simplified) translations for all UI elements in the Claude Code extension, including:

Chat input box placeholder text
Buttons and controls
Menu items
Settings labels
Error messages and notifications

Many Chinese-speaking developers use Claude Code, and having a fully localized interface would significantly improve the user experience and make the tool more accessible to the Chinese developer community.

The AI assistant already supports Chinese conversations perfectly, so adding UI localization would complete the Chinese language experience.

Thank you for considering this feature request!

Alternative Solutions

_No response_

Priority

Critical - Blocking my work

Feature Category

CLI commands and flags

Use Case Example

After setting VSCode's display language to Chinese (Simplified), most of VSCode's interface is properly localized, but the Claude Code extension UI elements (chat input placeholder, buttons, menu items, etc.) remain in English.

Additional Context

_No response_