docs: heznpc-session sweep — 5-label README + fix Node ≥22 drift + surface audit tools

[heznpc]

Summary

• Rewrite README + README.ko.md to the 5-label structure (Currently implemented / Planned / Design intent / Non-goals) and add the Part of: Human-Controlled AI Systems framing line.
• Fix README ↔ code drift: package.json requires Node ≥22 but the README still said ≥20. Now consistent.
• Surface the three audit MCP tools (audit_release, audit_cd, audit_security) in the ## Tools section with their CLI mirrors. Previously they were only referenced via the graduation guide link.
• Drop the lead "What it does" prose in favor of bulleted "Currently implemented" — every claim now maps to code or shipped text on disk.
• Korean README mirrored, formal honorifics (존댓말) preserved.

No code changes — README + README.ko.md only.

Test plan

• npm test — 85/85 pass (verified pre-PR)
• No code files touched
• CI green