Add full SEO optimization for Spanglish social and language events

- Add comprehensive metadata to root layout with Open Graph, Twitter cards
- Create dynamic sitemap.ts for all pages and events
- Create robots.ts with proper allow/disallow rules
- Add JSON-LD Event structured data to event detail pages
- Add page-specific metadata to events, community, contact, FAQ pages
- Add FAQ structured data schema
- Update footer with local SEO text for Asunción, Paraguay
- Add web manifest for mobile SEO
- Create 404 page with proper noindex
- Optimize image alt text and add lazy loading
- Add NEXT_PUBLIC_SITE_URL env variable
- Add about/ folder to gitignore

frontend/src/app/(public)/contact/layout.tsx

@@ -0,0 +1,18 @@
+import type { Metadata } from 'next';
+
+export const metadata: Metadata = {
+  title: 'Contact Us',
+  description: 'Get in touch with Spanglish. Questions about language exchange events in Asunción? We are here to help.',
+  openGraph: {
+    title: 'Contact Us – Spanglish',
+    description: 'Get in touch with Spanglish. Questions about language exchange events in Asunción? We are here to help.',
+  },
+};
+
+export default function ContactLayout({
+  children,
+}: {
+  children: React.ReactNode;
+}) {
+  return children;
+}