feat(website): add og:title and og:description via pageMeta helper

Extract a DRY pageMeta(title, description) helper that returns both
standard and OpenGraph meta tags from a single source of truth.

packages/website/src/meta.ts

@@ -0,0 +1,8 @@
+export function pageMeta(title: string, description: string) {
+  return [
+    { title },
+    { name: 'description', content: description },
+    { property: 'og:title', content: title },
+    { property: 'og:description', content: description },
+  ]
+}