Add CORS headers for data.json endpoint

Author: SableRaf

netlify.toml

@@ -14,4 +14,9 @@
 [[redirects]]
   from = "/_astro/PCD2026_og-image_tinyfied*"
   to = "/og-image.png"
-  status = 301
+  status = 301
+
+[[headers]]
+  for = "/data.json"
+  [headers.values]
+    Access-Control-Allow-Origin = "*"