feat: build the site with Astro Starlight

generate_site.py writes the Starlight project in website/ and nothing
else: mkdocs.yml, the MkDocs hooks, theme overrides and stylesheet go,
and the wiki is written in Starlight's syntax. Both workflows set up
Node with the official actions/setup-node pinned by commit, run npm ci
from the committed lockfile, build with the strict link validator and
check the result with validate_site.py.

The search weighs a page by what it answers: Start here pages first,
a system page's cards and file names before a guide citing them, deep
guides, launchers, aliases and frozen copies after. Status badges,
hash blocks and the export change lists leave the index. The ranking
sits at the centre of a range where the 13 queries of search_gate.py
all answer, in the search box itself.

839 pages, every URL and 45,611 ids match the MkDocs build. The tests
read the Starlight content and syntax.

website/astro.config.mjs

@@ -66,12 +66,21 @@ export default defineConfig({
 			expressiveCode: { defaultProps: { wrap: true } },
 			lastUpdated: false,
 			pagination: true,
-			// Measured on the ten queries of tools/search_gate.py, inside a range
-			// where all ten answer: Starlight's defaults (0.1, 0.1, 2, 9) let a guide
-			// that cites scph5501 once outrank the file's own card. A long page
-			// is penalised a little more, and how often a word appears counts.
+			// Measured on the queries of tools/search_gate.py, at the centre of a
+			// range where all of them answer. How often a word appears counts more
+			// than in Starlight's defaults (0.1, 0.1, 2, 9), a page's title weighs
+			// ten times its text, so "dolphin" finds Dolphin, and the file names of
+			// a system page (its `files` field, written by sitestarlight.py) count
+			// half, so "scph5501" finds the Sony page without a file name winning
+			// every other query.
 			pagefind: {
-				ranking: { pageLength: 0.3, termFrequency: 0.5, termSaturation: 1.4, termSimilarity: 9 },
+				ranking: {
+					pageLength: 0.1,
+					termFrequency: 0.5,
+					termSaturation: 1.4,
+					termSimilarity: 9,
+					metaWeights: { title: 10, files: 0.5 },
+				},
 			},
 			plugins: [
 				starlightSidebarTopics(sidebar.topics, sidebar.options),