feat: add explainable candidate ranking

[ECD5A]

Summary

• add deterministic, evidence-bearing multi-candidate ranking
• enforce framework, ownership, rights and bounded version constraints as hard gates
• add 8 independently specified adversarial goldens alongside the 50-case policy benchmark
• prepare synchronized 0.3.0 package, plugin and MCP Registry metadata
• make npm select the English README while preserving the full Russian README
• streamline historical and current release descriptions without changing the README animation

Verification

• npm run check
• npm run benchmark — 50/50 policy cases and 8/8 adversarial goldens
• live registry smoke test — 40/40 tests
• npm audit --omit=dev — 0 vulnerabilities
• npm dry-run package — 71.0 kB, English README.md