feat(FN-4400): complete Step 9 — docs and release notes

Fusion-Task-Id: FN-4400
Fusion-Task-Lineage: 0d4f9c48-5b8b-49eb-9cf3-d1d585ffe7fc

packages/engine/src/__tests__/heartbeat-executor.test.ts

@@ -2843,6 +2843,7 @@ describe("executeHeartbeat", () => {
         triggeringCommentIds: ["comment-1"],
         triggeringCommentType: "task",
         heartbeatScopeDiscipline: "strict",
+        heartbeatPromptTemplate: "default",
       });
     });