fix: request clipboardWrite permission for copy-markers button

The app runs in a sandboxed iframe — Clipboard API requires the host
to set allow="clipboard-write". Declare it via permissions metadata.

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

Author: ochafik

examples/map-server/server.ts

@@ -199,6 +199,8 @@ export function createServer(): McpServer {
           "https://*.cesium.com",
         ],
       },
+      // Clipboard permission for the copy-markers button
+      permissions: { clipboardWrite: {} },
     },
   };