feat: add X-Frame-Options DENY header

Prevent iframe embeds, Fixes ethereum/devops#1593

Author: wackerow

next.config.js

@@ -70,6 +70,19 @@ module.exports = (phase, { defaultConfig }) => {
         },
       ],
     },
+    async headers() {
+      return [
+        {
+          source: "/(.*)", // Apply to all routes
+          headers: [
+            {
+              key: "X-Frame-Options",
+              value: "DENY",
+            },
+          ],
+        },
+      ]
+    },
   }
 
   if (phase !== PHASE_DEVELOPMENT_SERVER) {