[ronaldtse]

Summary

Replaces the Starlight-based docs with the design system used by
the sibling browser site at https://opencdd.github.io/. Same color
palette, typography, and layout — adapted for a docs-only deployment.

Design system ported

• src/styles/global.css — the Tailwind v4 @theme block with the
  full OpenCDD palette (paper, ink, clay, teal, lapis, hex, coral)
  in light + dark + manual override variants. Copied verbatim.
• src/components/ui/SkipToContent.astro, Card.astro — direct ports.
• src/components/layout/Header.astro — simplified (drops command
  palette, dictionary nav, mobile nav, theme toggle). Docs nav: Home,
  Docs, GitHub, OpenCDD Browser.
• src/components/layout/Footer.astro — simplified footer with
  Project / Elsewhere nav.
• src/layouts/BaseLayout.astro, ProseLayout.astro, DocsLayout.astro
  — sidebar-aware docs layouts.
• src/lib/cn.ts — classname joiner.
• public/img/opencdd-logo_{light,dark}.svg + favicons + webmanifest.

Astro setup migrated from Starlight → vanilla Astro + Vue + MDX

• Dropped @astrojs/starlight, @astrojs/starlight-tailwind,
  @astrojs/tailwind (Tailwind v3 adapter).
• Added @astrojs/vue, @astrojs/mdx, @tailwindcss/vite (Tailwind v4
  via Vite plugin), vue, tailwindcss@^4.
• astro.config.mjs mirrors the sibling config: vue() + mdx() integrations,
  tailwindcss() Vite plugin.
• tsconfig.json adds ~ / ~/* path alias for src/.

Content collection restructured

• src/content.config.ts (Astro 5 path) replaces src/content/config.ts
  (Starlight path). Schema: title, description, published, updated,
  order, section, tags — matches the sibling's docs schema.
• All 10 existing markdown pages converted: added published: 2026-07-25
  • section + order. Bodies unchanged except stripping the duplicated
    # Title h1 (now provided by DocsLayout's header).
• Removed index.mdx (Starlight splash page); replaced with custom
  src/pages/index.astro hero.

New pages

• src/pages/index.astro — home page with hero, "What is opencdd?" cards,
  Ruby code sample, install snippet. Mirrors the sibling's hero styling.
• src/pages/docs/index.astro — docs landing page grouping entries by
  section with colored Card containers.
• src/pages/docs/[...slug].astro — dynamic per-doc route with sidebar
  nav and "Edit this page on GitHub" link.

Inert legacy files left in place

• src/styles/custom.css (Starlight CSS overrides) — kept per the
  "never delete source" rule; no longer loaded.
• src/assets/logo.svg — kept; superseded by public/img/.

Test plan

• Local: npm run build — 12 pages generated cleanly
• Local: npm run preview — home, docs index, docs/getting-started/,
  docs/ontology/ all render with design tokens (paper-50 backgrounds,
  ink-900 text, hex-600 accents)
• Each doc page has exactly one h1 (was previously duplicated)
• CI: docs workflow builds + deploys to Pages