Pixel-fidelity gate: standalone `omd verify <ref>` against the 246-ref catalog (de-risk)

[kwakseongjae]

Scope (the one genuinely-new build)

• Render DESIGN.md tokens via generate-css.ts + reference-preview.tsx → headless screenshot (Playwright MCP) → per-token-family diff with sharp (already a web dep): color (dominant swatch), radius (edge curvature), type (metrics), spacing.
• Report attribution per family, not one raw % (avoids webfont/antialiasing noise).
• Run FIRST as omd verify <ref> against the existing 246-ref catalog to validate the diff math against known-good fingerprints before exposing to user repos.

Acceptance

• omd verify <id> prints per-family fidelity %; scores stable across the catalog.

Depends on: none.