[Feature Request] Add Chinese (zh-CN/zh-TW) language support

[litt1esea]

Is your feature request related to a problem?
Many Chinese developers find it hard to use this framework due to the lack of Chinese documentation/UI.

Describe the solution you'd like
Add Simplified Chinese (zh-CN) localization support, including:

• Translated error messages in the core library.
• Chinese version of the official docs (can start with README).