feat: surface auto project sync guidance in master chat

tests/device-import-draft.test.ts

@@ -617,6 +617,13 @@ test("imported thread projects queue hidden understanding sync tasks on newer ac
       /实时状态同步和 UI 联调阶段/.test(message.body),
   );
   assert.ok(syncNotice, "expected master-agent conversation to receive a lightweight sync digest");
+  const nextStepNotice = masterAgentProject?.messages.findLast(
+    (message) =>
+      message.kind === "system_notice" &&
+      /建议下一步推进：智能看板主线程/.test(message.body) &&
+      /优先压平实时状态刷新抖动，再验证群聊调度链路。/.test(message.body),
+  );
+  assert.ok(nextStepNotice, "expected master-agent conversation to receive a lightweight next-step suggestion");
 });
 
 test("heartbeat candidates no longer auto-create chat windows from legacy projects when import draft is present", async () => {