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/detect.mjs

@@ -0,0 +1,21 @@
+#!/usr/bin/env node
+
+import fs from 'node:fs';
+import path from 'node:path';
+import { pathToFileURL, fileURLToPath } from 'node:url';
+
+const __dirname = path.dirname(fileURLToPath(import.meta.url));
+const candidates = [
+  path.join(__dirname, 'detector', 'detect-antipatterns.mjs'),
+  path.join(__dirname, '..', '..', 'cli', 'engine', 'detect-antipatterns.mjs'),
+];
+const detectorPath = candidates.find(p => fs.existsSync(p));
+
+if (!detectorPath) {
+  process.stderr.write('Error: bundled detector not found.\n');
+  process.exit(1);
+}
+
+const { detectCli } = await import(pathToFileURL(detectorPath));
+
+await detectCli();