init: centralized agent skills for Claude Code + Codex

- skills/ shared by both tools (open Agent Skills standard)
- portable cross-skill refs (root-relative, no ~/.claude hardcode)
- bin/link.sh bootstrap for non-Nix machines
- nix/home.nix + flake.nix for home-manager

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014SK5Lo7LQfwLRVdCv1A8uF

skills/impeccable/scripts/detector/findings.mjs

@@ -0,0 +1,12 @@
+import { getAntipattern } from './registry/antipatterns.mjs';
+
+function getAP(id) {
+  return getAntipattern(id);
+}
+
+function finding(id, filePath, snippet, line = 0) {
+  const ap = getAP(id);
+  return { antipattern: id, name: ap.name, description: ap.description, severity: ap.severity || 'warning', file: filePath, line, snippet };
+}
+
+export { getAP, finding };