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/public/manifest.json

@@ -0,0 +1,27 @@
+{
+  "name": "Spanglish – Language Exchange Events in Asunción",
+  "short_name": "Spanglish",
+  "description": "Practice English and Spanish at relaxed social events in Asunción, Paraguay. Meet locals and internationals.",
+  "start_url": "/",
+  "display": "standalone",
+  "background_color": "#FFFFFF",
+  "theme_color": "#FFD700",
+  "orientation": "portrait-primary",
+  "scope": "/",
+  "lang": "en",
+  "categories": ["events", "social", "education"],
+  "icons": [
+    {
+      "src": "/images/icon-192.png",
+      "sizes": "192x192",
+      "type": "image/png",
+      "purpose": "any maskable"
+    },
+    {
+      "src": "/images/icon-512.png",
+      "sizes": "512x512",
+      "type": "image/png",
+      "purpose": "any maskable"
+    }
+  ]
+}