docs: restructure bilingual documentation with English default and independent Chinese version (#13)

docs: restructure README into bilingual documentation

Split the monolithic bilingual README into separate English (README.md)
and Simplified Chinese (README_zh.md) files, with README_EN.md acting
as a redirect to the primary English documentation.

Rewrite both READMEs with a consistent, modern layout featuring badges,
a gating architecture diagram, installation/load order, and testing
instructions. This removes the previously duplicated sub-module tables,
settings references, and FAQ content in favor of a concise overview.

BREAKING CHANGE: README_EN.md no longer contains documentation and now
only redirects to README.md.

Author: mcocdaa