Add graceful SCUM stop, restart, and version update flow

SCUM 停止/重启/更新以前只有“结束进程”这一条路，插件没有声明任何优雅关闭方式，
平台也没有把停止后重新启动串起来。现在插件声明自己的关闭脚本，run 先执行它，
平台在停止或更新成功后再自动拉起服务。

run:
- lifecycle stop 支持插件声明的 gracefulStop（可执行文件、参数、环境、超时、
  fallback=report|terminate）；关闭命令超时且声明 report 时任务失败，不再默默杀进程。
- 新增 steam.update 依赖探针：调用 steamcmd +app_info_print 获取公开分支 buildid，
  与本地 steamapps/appmanifest_<appid>.acf 的 buildid 比较，输出
  installed/latest/update=yes|no|unknown。

platform:
- 新增 POST /api/v1/server-instances/{id}/restart 与 /update。
- restart 派发插件 stop 动作（走优雅关闭），终态成功后入队 start 作业。
- update 派发插件 install 动作；插件在更新前必须先优雅关闭 SCUM，关闭失败直接拒绝
  SteamCMD 更新，成功后平台再拉起服务。
- 依赖检查输入带上插件声明的服务器安装根目录，供 steam.update 读取 appmanifest。

plugin (SCUM server plugin 0.1.16):
- bin/scum-stop.cmd：解析已声明的可执行文件路径，定位同路径正在运行的 SCUMServer.exe，
  通过本地 RCON 公告并发送关闭命令，等待进程自行退出；不再使用 taskkill。
- bin/scum-rcon.ps1：插件自有的 Source RCON 客户端，从 UE4SS mod config.ini 读取
  密码/端口，密钥不离开本机。
- actions/stop.json 声明 gracefulStop；actions/install.json 更新前先执行同一关闭脚本。

platform_web:
- 服务器详情新增“重启”按钮和“SCUM 版本更新”面板；点“检查更新”查询公开分支版本，
  只有检测到更新时“更新版本”按钮才会置为可用并高亮，点击后先确认再派发更新任务。

platform_web/api/client.test.ts

@@ -385,6 +385,14 @@ describe("PlatformApiClient AI providers", () => {
       if (url.endsWith("/api/v1/server-instances/server-1/stop") && init?.method === "POST") {
         return jsonResponse({ accepted: true, action: "stop", instance: server, job: { ...job, capability: "process.stop" } });
       }
+      if (url.endsWith("/api/v1/server-instances/server-1/restart") && init?.method === "POST") {
+        expect(JSON.parse(String(init.body))).toEqual({ expectedConfigVersion: 1, idempotencyKey: "idem-restart" });
+        return jsonResponse({ accepted: true, action: "restart", instance: server, job: { ...job, capability: "process.stop" } });
+      }
+      if (url.endsWith("/api/v1/server-instances/server-1/update") && init?.method === "POST") {
+        expect(JSON.parse(String(init.body))).toEqual({ expectedConfigVersion: 1, idempotencyKey: "idem-update" });
+        return jsonResponse({ accepted: true, action: "update", instance: server, job: { ...job, capability: "process.install" } });
+      }
       if (url.endsWith("/api/v1/server-instances/server-1/process/status") && init?.method === "POST") {
         return jsonResponse({ accepted: true, action: "status", instance: server, job: { ...job, capability: "process.status", executionResult: { kind: "process", processState: "running", summary: "private supervised process identity" } } });
       }
@@ -604,6 +612,8 @@ describe("PlatformApiClient AI providers", () => {
     });
     await expect(client.startServerInstance(server.id, { expectedConfigVersion: 1, idempotencyKey: "idem-start" })).resolves.toMatchObject({ action: "start" });
     await expect(client.stopServerInstance(server.id, { expectedConfigVersion: 1, idempotencyKey: "idem-stop" })).resolves.toMatchObject({ action: "stop" });
+    await expect(client.restartServerInstance(server.id, { expectedConfigVersion: 1, idempotencyKey: "idem-restart" })).resolves.toMatchObject({ action: "restart", job: { capability: "process.stop" } });
+    await expect(client.updateServerGame(server.id, { expectedConfigVersion: 1, idempotencyKey: "idem-update" })).resolves.toMatchObject({ action: "update", job: { capability: "process.install" } });
     await expect(client.queryServerProcessStatus(server.id, { expectedConfigVersion: 1, idempotencyKey: "idem-status" })).resolves.toMatchObject({ action: "status", job: { executionResult: { processState: "running" } } });
     await expect(client.listServerAdministratorCandidates(server.id)).resolves.toMatchObject({ count: 1 });
     await expect(client.addServerAdministrator(server.id, { userId: "user-2" })).resolves.toMatchObject({ adminUserIds: ["user-admin-1", "user-2"] });
@@ -637,7 +647,7 @@ describe("PlatformApiClient AI providers", () => {
       client.invokeAI({ requestId: "ai-1", serverInstanceId: server.id, purpose: "config.suggest", prompt: "Tune PVP safely", currentConfig: "server.name=Example Survival #1\n" })
     ).resolves.toMatchObject({ status: "ok", usage: { mocked: true }, configRecommendation: { diffSummary: "review required" } });
 
-    expect(fetchMock).toHaveBeenCalledTimes(49);
+    expect(fetchMock).toHaveBeenCalledTimes(51);
   });
 
   it("normalizes server file workspace null arrays from older platform responses", async () => {