docs(i18n): add Simplified Chinese translation of README

Translate README.md to Simplified Chinese as README.zh-CN.md with a
top-level note that the English version is authoritative.

Preserved verbatim:
- All 7 mermaid diagrams (node labels translated, syntax preserved)
- All code blocks (bash, python, bibtex)
- Badge URLs, image links, table column headers
- Author name (Yu Ching Lam), MIT license, commit hashes
- All numerical values: 0.9845, 0.9746, 0.9887, 5,738, 228 tests, etc.

Translation preserves:
- Honest framing: "honest bottom line" -> "最诚实的结论",
  "honest negative results" -> "诚实阴性结果"
- Section structure (13 H2 sections matching English)
- 1041 lines vs 1082 EN (minor compression from translated prose)

Verified:
- 228/228 tests pass
- 54 fenced code blocks (27 pairs), all balanced
- 167 well-formed markdown tables
- All brackets balanced: () {} []

Author: hermes-agent