fix: strip invalid as:Endpoints type from Fedify actor serialization

Fedify serializes the endpoints object with "type": "as:Endpoints" which
is not a valid ActivityStreams 2.0 type. This causes browser.pub validation
failures. Strip the type field in the JSON patching block.

Confab-Link: http://localhost:8080/sessions/af5f8b45-6b8d-442d-8f25-78c326190709

lib/federation-bridge.js

@@ -89,6 +89,12 @@ async function sendFedifyResponse(res, response, request) {
       if (json.attachment && !Array.isArray(json.attachment)) {
         json.attachment = [json.attachment];
       }
+      // WORKAROUND: Fedify serializes endpoints with "type": "as:Endpoints"
+      // which is not a valid AS2 type. The endpoints object should be a plain
+      // object with just sharedInbox/proxyUrl etc. Strip the invalid type.
+      if (json.endpoints && json.endpoints.type) {
+        delete json.endpoints.type;
+      }
       const patched = JSON.stringify(json);
       res.setHeader("content-length", Buffer.byteLength(patched));
       res.end(patched);