feat(site): phase 1 — the foundation

Astro 7 with the Node adapter, Starlight mounted at /docs, the token file, both
self-hosted typefaces, the layout shell, and the two build-time checks from §12.

The palette's gold and cyan are sampled from runic-emblem.png rather than
guessed, per §11: 494,059 opaque pixels binned by hue, each value annotated with
its measured contrast against the ground, and restricted rather than brightened
where a ratio fails.

- checkTokens.mjs fails the build on any colour literal outside tokens.css,
  which is what keeps §7's "recolouring is a file copy" promise true.
- checkFacts.mjs re-reads all 14 externally-sourced facts from their authorities
  over the Gitea API and fails on disagreement. It also enforces D13: no email
  address in the source outside brand-default/brand.json.
- Both were negative-tested; neither has ever been allowed to pass by default.

§6 asks for output:'server' with per-page prerender=true. Astro 7 expresses the
same runtime shape as output:'static' with an adapter, opting individual routes
out — so the default is static rather than accidentally server-rendered.

Co-Authored-By: Claude <noreply@anthropic.com>

astro.config.mjs

@@ -0,0 +1,59 @@
+// @ts-check
+import { defineConfig } from 'astro/config';
+import node from '@astrojs/node';
+import starlight from '@astrojs/starlight';
+
+import { docsSidebar } from './src/config/sidebar.mjs';
+
+/**
+ * PLAN.md §6 calls this "Astro with the Node adapter, `output: 'server'` with per-page
+ * `prerender = true`". Astro 7 expresses that shape the other way round: `output: 'static'`
+ * with an adapter prerenders everything and lets individual routes opt OUT with
+ * `export const prerender = false`. The runtime result is identical to what §6 describes —
+ * a container serving prerendered HTML, with a handful of routes executing per request —
+ * and this is the direction the framework supports, so the default is the safe one: a page
+ * added without thinking about it is static, not accidentally server-rendered.
+ *
+ * The two routes that will opt out live in phases 2 and 5: `GET /brand/*` (§7) and
+ * `POST /api/beta-signup` (§8).
+ */
+export default defineConfig({
+  site: 'https://runicgateway.com',
+  output: 'static',
+  adapter: node({ mode: 'standalone' }),
+
+  build: {
+    // Directory-style URLs, so every link in prose can end in a slash and mean it.
+    format: 'directory',
+  },
+
+  integrations: [
+    starlight({
+      title: 'Runic Gateway',
+      // Marketing owns the 404 (§10); a Starlight-chrome 404 on `/features/` would be wrong.
+      disable404Route: true,
+      // Starlight's own light/dark switch is deliberate: §11 keeps marketing single-theme
+      // but has the docs honour the reader's preference.
+      customCss: ['./src/styles/tokens.css', './src/styles/starlight.css'],
+      components: {
+        // Not the `logo` option: that renders an <img>, and our mark is drawn in
+        // currentColor so it inherits --gold and follows a mounted theme.css. An SVG
+        // loaded through <img> is a separate document with nothing to inherit from, so it
+        // renders black on black. The override inlines it instead — see the component.
+        SiteTitle: './src/components/DocsSiteTitle.astro',
+      },
+      credits: false,
+      sidebar: docsSidebar,
+      pagination: true,
+      lastUpdated: false,
+      editLink: {
+        baseUrl: 'https://gitea.whitlocktech.com/RunicGateway/runicgateway.com/_edit/main/',
+      },
+    }),
+  ],
+
+  prefetch: {
+    prefetchAll: true,
+    defaultStrategy: 'hover',
+  },
+});