feat: migrate blog FAQs to reusable MDX accordion

- add Astro MDX support and convert FAQ-bearing posts to MDX
- centralize FAQ markup, scoped styling, behavior, and JSON-LD
- preserve FAQ content and links across English and Spanish posts
- extend blog audits and document the MDX editing workflow
- remove obsolete global FAQ styles
- ignore Front Matter CMS generated state

www/astro.config.mjs

@@ -1,8 +1,10 @@
 import { defineConfig } from 'astro/config';
+import mdx from '@astrojs/mdx';
 
 export default defineConfig({
   site: 'https://www.azinstitute4autism.com',
   trailingSlash: 'never',
+  integrations: [mdx()],
   markdown: {
     shikiConfig: { theme: 'github-light' }
   }