docs: refactor README onboarding

[pDJJq]

Summary

• Rework the English and Chinese READMEs around product value, executable 60-second starts, daily retrieval, and safety boundaries.
• Separate judgment-bearing Agent workflows from the deterministic runtime CLI.
• Move the portable AGENTS.md integration contract into a focused reference document.
• Sync llmdoc release knowledge with the new document owner and the official-host documentation review invariant.

Verification

• npm run typecheck
• npm run lint
• npm test
• npm run build
• npm run validate:dogfood
• npm run check:prompts
• node scripts/check-codex-surface.mjs
• npx -y markdownlint-cli2 README.md README.zh-CN.md docs/agent-integration.md
• Bilingual command parity, local link resolution, and README CLI examples verified