feat(frontend): redesign UI and self-host OFL fonts

[DataGomes]

Summary

• Frontend redesign: cohesive editorial "Observatory" aesthetic (warm dark palette, Instrument Serif display + Geist body + Geist Mono data, hairline rules, tabular numerics, quieter score gradient). Touches login, chat, results index + detail, and history.
• Self-host three font families under SIL Open Font License 1.1 with explicit attribution in /THIRD_PARTY and bundled OFL.txt — removes the build-time dependency on fonts.gstatic.com and makes AWS Labs OSS compliance auditable.

What changed visually

• Login: bright-white sign-in flash → editorial cover with italic ember accent
• Chat: bubble chat → editorial transcript with mono role/time eyebrows
• Results index: card grid → typographic table of contents with status glyphs and tabular score chips
• Results detail: dense data display with large serif overall scores, per-criterion tables with hairline rules, tinted score cells, and a focused side detail panel
• History: archive treatment with master/detail and consistent header

Design tokens consolidated into tailwind.config.ts and globals.css as semantic names (ink, bone, rule, ember, sage, wheat, oxide) — no more ad-hoc claude-* colour classes scattered across components.

License and compliance (AWS Labs)

• All bundled fonts are SIL Open Font License 1.1, distributed unmodified from upstream
• 4 woff2 files committed under frontend/app/fonts/ (~175 KB total)
• SHA256 hashes pinned in frontend/app/fonts/SHA256SUMS for integrity verification
• Canonical OFL 1.1 license text + per-font copyright statements bundled in frontend/app/fonts/OFL.txt
• 3 attribution entries added to /THIRD_PARTY matching the existing format (Geist, Geist Mono, Instrument Serif)
• Project code stays Apache 2.0 (LICENSE unchanged)

Sources:

• Geist + Geist Mono: https://github.com/vercel/geist-font (Copyright 2024 The Geist Project Authors)
• Instrument Serif: https://github.com/Instrument/instrument-serif (Copyright 2022 The Instrument Serif Project Authors)

Verification

• tsc --noEmit → clean
• BUILD_MODE=standalone next build → clean, all routes prerender
• BUILD_MODE=export next build → clean (the static export consumed by the eval_mcp viewer)
• All 4 self-hosted fonts emitted into .next/static/media/ byte-identical to the upstream files
• 9 Playwright screenshots across /, /chat, /results, /results?group=..., /history with realistic mocked API data — 0 console errors, 0 console warnings

Side effect: dev hot-reload restored

next dev previously hung indefinitely on /chat due to a Turbopack + next/font/google interaction (font refetch at compile time). Switching to next/font/local removes the runtime Google dependency and unbreaks next dev for local frontend iteration.

Known gaps (deliberately deferred — happy to follow up)

• prefers-reduced-motion not yet respected in keyframe animations
• Focus-visible rings missing on most nav buttons / sidebar items / comparison cells
• bone-mute (#6f6759) on ink (#0c0a08) is ~3.7:1 — below WCAG AA for normal-size body text; used on eyebrows and metadata in several places
• Navigation uses <button onClick={router.push(...)}> instead of <Link href> (loses prefetching, right-click "copy link", middle-click new tab, and proper screen-reader link semantics)
• aria-current="page" missing on active nav items
• scoreColor helper duplicated across four components (should be one lib/score.ts)
• Legacy claude-* Tailwind aliases left in tailwind.config.ts as a safety net during the migration — now unused and removable

Test plan

• npm run build:viewer in frontend/, hard-reload localhost:4001/results — verify the redesign renders with real eval data
• npm run dev in frontend/ — verify /chat no longer hangs (was broken pre-PR)
• BUILD_MODE=standalone npm run build — verify the EKS-deployable bundle still produces
• Review the 3 new entries in /THIRD_PARTY and the bundled OFL.txt for license-review correctness
• (Optional) Verify SHA256 sums against upstream sources before merging