docs: Black-hole zombie pages

.cloudflare/docs-proxy/src/worker.js

@@ -3,6 +3,15 @@ export default {
     const url = new URL(request.url);
     url.hostname = "docs-anw.pages.dev";
 
+    // These pages were removed, but may still be served due to Cloudflare's
+    // [asset retention](https://developers.cloudflare.com/pages/configuration/serving-pages/#asset-retention).
+    if (
+      url.pathname === "/docs/assistant/context-servers" ||
+      url.pathname === "/docs/assistant/model-context-protocol"
+    ) {
+      return await fetch("https://zed.dev/404");
+    }
+
     let res = await fetch(url, request);
 
     if (res.status === 404) {