docs: split bilingual open-source readmes

[Pigbibi]

Summary

• replace the mixed-language README with an English-only open-source entry point
• add a separate Chinese README.zh-CN.md with the same project overview structure
• include explicit risk notices, quick start, deployment guidance, and evidence boundaries

Validation

• verified README.md contains no Chinese characters
• verified README.zh-CN.md exists and contains the Chinese risk notice
• verified only README.md and README.zh-CN.md changed

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Install test requirements before running pytest

For the documented “fresh clone” path, python -m pip install -e . installs only the [project].dependencies from pyproject.toml, which do not include pytest; pytest is only listed in requirements.txt and CI installs that file before running tests. In a clean environment this leaves the next command, python -m pytest -q, failing before any tests run, so the quick start should install the test requirements (or document -r requirements.txt) first.

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