docs: add Chinese translation (README.zh.md) to improve accessibility

[JasonYeYuhe]

PR Description: docs: add Chinese translation (README.zh.md)

Overview

Claude Code is quickly becoming a staple in modern developer workflows. To help the massive Chinese-speaking developer community adopt and integrate this tool more easily, this PR introduces a precise Chinese translation of the README.md.

Changes

• README.zh.md: Created a complete Chinese translation that mirrors the English original, including all installation instructions and plugin documentation links.
• Language Switcher: Added an English · 中文 toggle in the main README.md, positioned prominently below the main badges for maximum discoverability.

Translation Philosophy

• Developer-Centric Context: Retained core terms like "IDE" and "Agent", while translating "agentic coding tool" to its accepted Chinese equivalent (编程智能体) to ensure the concept is clear to the local community.
• Structural Integrity: 100% parity with the English original.
• Sync Note: Included a hidden HTML comment at the top of the translated file to remind future contributors to maintain parity with the English version.

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Contribution by JasonYeYuhe.