整合求解器活动监控与步长回归证据

同步远端 PNL0003 诊断和大采样网格能力，语义合并活动感知的 60 秒真停滞判定与旧后端 15 分钟兼容兜底。

纳管热路径优化、15 单元运行证据、浏览器与 API 报告，并补充北京时间更新日志和遗留问题。

frontend/tests/e2e/simulation-timeout.spec.ts

@@ -1,8 +1,11 @@
 import { expect, test } from "@playwright/test";
 
 import {
+  SIMULATION_ACTIVITY_STALL_TIMEOUT_MS,
+  SIMULATION_ACTIVITY_STALL_TIMEOUT_SECONDS,
   SIMULATION_SOLVER_STALL_TIMEOUT_MINUTES,
   SIMULATION_SOLVER_STALL_TIMEOUT_MS,
+  solverActivityStallTimeoutMessage,
   solverStallTimeoutMessage,
   solverStallTimeoutReached,
 } from "../../src/simulationTimeout";
@@ -19,3 +22,11 @@ test("solver stall messages use the configured duration", () => {
   expect(solverStallTimeoutMessage("recovering")).toContain("连续 15 分钟");
   expect(solverStallTimeoutMessage("recovering")).toContain("恢复部分结果");
 });
+
+test("activity-aware watchdog keeps its shorter true-stall threshold", () => {
+  expect(SIMULATION_ACTIVITY_STALL_TIMEOUT_SECONDS).toBe(60);
+  expect(SIMULATION_ACTIVITY_STALL_TIMEOUT_MS).toBe(60_000);
+  expect(solverActivityStallTimeoutMessage("detected")).toContain(
+    "接受步和内部活动均连续 60 秒",
+  );
+});