SEO: robots.txt, sitemap, Organization & Event schema; dashboard fmtTime fix; frontend updates

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/app/(public)/page.tsx

@@ -66,6 +66,7 @@ export async function generateMetadata(): Promise<Metadata> {
     year: 'numeric',
     month: 'long',
     day: 'numeric',
+    timeZone: 'America/Asuncion',
   });
 
   const description = `Next event: ${eventDate} – ${event.title}. Practice English and Spanish at relaxed social events in Asunción. Meet locals and internationals.`;