维护者确认：#3344 空闲 worker 退出后再重启

## 需要维护者确认的点

PR https://github.com/makecindy/cindy/pull/3344 同样改 `nodeRuntimeBroker`：按 key 保存停止退出屏障，旧进程未退出则有界失败、不双开。

插件基座路径改动不走 bugfix 豁免。请维护者确认：

1. 「等待真实 exit，超时则启动失败」对存量按需插件是否安全；
2. 与同题 #3343 的差异（实现与错误口径）要以哪一边为准，避免两条并行合入。

## 如何放行

- 同意：直接在 PR 上 **Approve**。
- 要改：在 PR 上 **Request Changes**。

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关联 PR:#3344(作者 @nothingyuancando);本 issue 由 review-pr 流程自动创建,用于先讨论该 PR 涉及的插件基座改动(影响全部已装插件),维护者确认后 PR 会恢复推进。

Start by reviewing PR #3344 and the nodeRuntimeBroker changes described there, then compare them with issue #3343. The maintainer must decide whether waiting for a real exit with bounded failure is safe for existing on-demand plugins and which implementation and error wording should proceed; no implementation task is specified here.

Written by the indexing model from the issue text.