Support declared graceful stop and steam.update probe

- LifecycleActionTemplate 新增 gracefulStop：stop 动作可声明插件自有的优雅关闭命令、
  参数、环境、超时与 fallback；超时且 fallback=report 时任务失败，避免默认杀进程。
- 依赖探针新增 steam.update：通过 steamcmd +app_info_print 读取公开分支 buildid，
  与本地 appmanifest_<appid>.acf 比较，输出 installed/latest/update=yes|no|unknown。
- 依赖执行输入新增 ServerRoot，供探针定位插件声明的服务器安装目录。

runtime/autonomous_lifecycle.go

@@ -193,7 +193,11 @@ func (worker *Worker) runAutonomousDependencies(ctx context.Context, plan protoc
 		return nil
 	}
 	for _, probe := range plan.DependencyProbes {
-		state, evidence, err := worker.executor.runDependencyProbe(ctx, probe, plan.RuntimeBindings)
+		installRoot := ""
+		if plan.Deployment != nil {
+			installRoot = plan.Deployment.ServerRoot
+		}
+		state, evidence, err := worker.executor.runDependencyProbe(ctx, probe, plan.RuntimeBindings, installRoot)
 		if err != nil {
 			if probe.Required {
 				log.Printf("RUN phase=autonomous_lifecycle.dependencies status=failed probe=%s error=%s", safeOptional(probe.Key), err.Error())