docs: add in-page bilingual project guides

[KXHXK]

Summary

• switch README and CONTRIBUTING between Chinese and English in place with grouped GitHub details panels
• expand the README technology badges and keep only the public project URL
• record a specification-alignment and release-readiness audit

Verification

• targeted release/document-index suite: 14 passed
• repository safety: passed
• local Markdown links and project-focus scan: passed
• GitHub Markdown rendering preserves both grouped details panels and the default open panel
• Netlify static routes return 200; local demo readiness reports database/checkpoint/MCP ready
• release Compose configuration validates

Boundaries

The public Netlify site remains static. This PR does not expose the API or change the closed production release gate.