update: improve SEO - absolute OG image URLs, add sitemap and robots.txt

- Use absolute URLs for OG/Twitter images (required by LinkedIn, WhatsApp)
- Add image type and descriptive alt text for OG image
- Add robots.txt allowing all crawlers
- Add dynamic sitemap.xml with all public pages

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/layout.tsx

@@ -28,10 +28,11 @@ export const metadata: Metadata = {
     siteName: "Crypto Commons Gathering",
     images: [
       {
-        url: "/og-image.jpg",
+        url: "https://cryptocommonsgather.ing/og-image.jpg",
         width: 1200,
         height: 630,
-        alt: "Crypto Commons Gathering 2026 - Austrian Alps",
+        alt: "Commons Hub in Austria's Höllental Valley with yellow tulips in foreground",
+        type: "image/jpeg",
       },
     ],
     locale: "en_US",
@@ -42,7 +43,14 @@ export const metadata: Metadata = {
     title: "Crypto Commons Gathering 2026 | CCG",
     description:
       "The sixth annual hack-ademic confluence of commons praxis and the latest cryptographic technologies in the Austrian Alps. August 16-23, 2026.",
-    images: ["/og-image.jpg"],
+    images: [
+      {
+        url: "https://cryptocommonsgather.ing/og-image.jpg",
+        width: 1200,
+        height: 630,
+        alt: "Commons Hub in Austria's Höllental Valley with yellow tulips in foreground",
+      },
+    ],
   },
 }
 

app/sitemap.ts

@@ -0,0 +1,15 @@
+import type { MetadataRoute } from "next"
+
+export default function sitemap(): MetadataRoute.Sitemap {
+  const baseUrl = "https://cryptocommonsgather.ing"
+
+  return [
+    { url: baseUrl, lastModified: new Date(), changeFrequency: "weekly", priority: 1.0 },
+    { url: `${baseUrl}/register`, lastModified: new Date(), changeFrequency: "weekly", priority: 0.9 },
+    { url: `${baseUrl}/about`, lastModified: new Date(), changeFrequency: "monthly", priority: 0.8 },
+    { url: `${baseUrl}/directions`, lastModified: new Date(), changeFrequency: "monthly", priority: 0.7 },
+    { url: `${baseUrl}/transparency`, lastModified: new Date(), changeFrequency: "monthly", priority: 0.6 },
+    { url: `${baseUrl}/gallery`, lastModified: new Date(), changeFrequency: "monthly", priority: 0.6 },
+    { url: `${baseUrl}/sponsorships`, lastModified: new Date(), changeFrequency: "monthly", priority: 0.5 },
+  ]
+}

public/robots.txt

@@ -0,0 +1,4 @@
+User-agent: *
+Allow: /
+
+Sitemap: https://cryptocommonsgather.ing/sitemap.xml