docs: site WIP, extractor type cleanup, tests preset; add broadcastedRef

Type the docs extractor's package.json parsing as unknown; comment the Vite
plugin version-skew cast; wire the tests preset; site/architecture WIP.

docs/nuxt.config.ts

@@ -20,6 +20,8 @@ export default defineNuxtConfig({
 
   vite: {
     plugins: [
+      // `as any`: @tailwindcss/vite and Nuxt resolve different `vite` versions, so
+      // their `Plugin` types are structurally identical but nominally incompatible.
       tailwindcss() as any,
     ],
   },