test(specimens): add reviewable viewport receipts

[BunsDev]

Objective

Make visual changes to the specimen browser inspectable in review instead of relying on an unrecorded manual spot-check.

This PR is stacked on #1 and should merge after it.

What changed

• adds a dependency-free Chrome DevTools Protocol renderer for the specimen app
• captures five deliberate receipts across Library / Assembled, dark / light, cozy / compact, desktop / 390 px mobile
• asserts visible shell landmarks, zero horizontal overflow, persisted scheme and density, all 16 library specimens, all three catalog groups, all five assembled tabs, and no runtime or console errors
• uploads PNGs, a machine-readable summary, a Markdown summary, the Vite preview log, and a Chrome log on failure
• documents what a green result proves—and what still requires human visual judgment
• pins the Chrome setup action to an immutable commit

Deliberate non-goals

• no pixel-perfect golden-image baseline
• no Playwright, Puppeteer, or other package dependency
• no exported UI behavior or token changes
• no replacement for product-level visual testing in Cave

Verification before opening

• repository-pinned Prettier applied to the script and handoff
• node --check scripts/visual-review.mjs — pass
• final intended file set: .github/workflows/visual-review.yml, scripts/visual-review.mjs, handoffs/visual-review.md

The PR remains a draft until the normal pnpm check gate and the new visual-review workflow both pass and the produced receipts are inspected.

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
opencoven-ui	Ready	Preview	Aug 30, 2026 2:32pm
ui	Error		Aug 30, 2026 2:32pm