docs: maintainer edit — CLAUDE.md still lists "Fallback: Nix (flake.nix)"

[hyperpolymath]

The estate wave removed flake.nix (PR #72); the Package Management section in .claude/CLAUDE.md (~line 96) is now stale. Guardrail-protected file.

https://claude.ai/code/session_01GJatEm2TVFSTBEkKXmserJ