chore: get DESIGN.md on par with upstream design.md 0.2.0 (Tailwind v4 export shipped)

[VirtueMe]

Context

google-labs-code/design.md released 0.2.0 (last pushed 2026-06-03, very active — 15k+ stars). Our DESIGN.md tooling note (Validation section, ~line 115) is now partially stale: it describes Tailwind v4 export as "pending upstream (issue #19)," but #19 is closed and the export shipped (PR #45, hardened by #25/#71/#72).

We pull the linter via npx --yes @google/design.md (package.json validate:design), so the lint side is already current. This issue is about closing the docs gap and acting on what the new export unblocks.

Tasks

• Update the Validation section of DESIGN.md: Tailwind v4 export has landed — drop the "pending issue fix: revert to GH_TOKEN in release workflow #19" language. Keep the WCAG-contrast caveat (still aspirational; closest is opt-in color-blind rule #48, still open).
• Evaluate wiring automatic token sync into docs/.vitepress/theme/custom.css using the css-tailwind export, as the old note anticipated. Spike it; if it's not worth the complexity, record why and close that thread.
• Note newly available capabilities for future reference: OKLCH / alpha / 8-digit hex color support (docs: refactor CLAUDE.md into focused documentation files #27/docs: clarify 'rebase' terminology to 'squash' in workflow documentation #52/docs: enhance CLAUDE.md with comprehensive onboarding and best practices #53), proposed --format css-vars export (#15, still open — may be a better fit than Tailwind for our plain-CSS theme).
• Confirm DESIGN.md still lints clean against 0.2.0 (new unknown-key rule chore: configure semantic-release to trigger versions on style commits #84 could flag something).

Out of scope

• Adopting OKLCH / css-vars now — just documenting availability. Pin only if a future need appears.

Acceptance

• DESIGN.md Validation section reflects 0.2.0 reality (no stale "pending" claims).
• Token-sync spike has a decision recorded (wired up, or deferred with rationale).

[claude]

Thanks for the detailed write-up, @VirtueMe! Triaged with the following labels:

• docs — the core work is updating DESIGN.md to reflect 0.2.0 reality (dropping the stale "pending issue fix: revert to GH_TOKEN in release workflow #19" language and noting newly available capabilities)
• enhancement — the token-sync spike is an additive improvement, not a bug fix
• priority: low — no functionality is broken; this is documentation maintenance to close the gap with an upstream release

This repo doesn't have a chore label, so docs + enhancement best captures the two tracks here. A maintainer can adjust priority if the token-sync spike turns out to be worth fast-tracking.