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

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

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

@@ -20,7 +20,7 @@ export const metadata: Metadata = {
 const organizationSchema = {
   '@context': 'https://schema.org',
   '@type': 'Organization',
-  name: 'Spanglish',
+  name: 'Spanglish Community',
   url: siteUrl,
   logo: `${siteUrl}/images/logo.png`,
   description: 'Language exchange community organizing English and Spanish meetups in Asunción, Paraguay.',
@@ -30,7 +30,7 @@ const organizationSchema = {
     addressCountry: 'PY',
   },
   sameAs: [
-    process.env.NEXT_PUBLIC_INSTAGRAM_URL,
+    'https://instagram.com/spanglishsocialpy',
     process.env.NEXT_PUBLIC_WHATSAPP_URL,
     process.env.NEXT_PUBLIC_TELEGRAM_URL,
   ].filter(Boolean),