Windows CI: packaged-instance barrier probe times out

PR #4146 的 client-ci Windows unit tests (1/2) 在既有 Windows 专属用例 `windowsPackagedInstanceBarrier.test.ts > holds the packaged startup mutex until release and allows a later retry` 失败。

日志：https://github.com/makecindy/cindy/actions/runs/34309831415/job/102334019871
Head: 95eeda0fa15da06668605fb4ada7dd7f88dae085
错误：`timed out probing Windows packaged-instance barrier`，来自 waitForBarrierStatus 的 probing 超时，尚未进入正常 mutex 等待。

该测试与 windowsPackagedInstanceBarrier.ts 相对 upstream/main 无差异，授权卡 PR 未修改二者。Linux 两个分片与 verify-checks 通过。应在 Windows 核查 PowerShell 冷启动/Add-Type 探测是否卡住或预算受负载影响，保留独占、释放与后续重试断言，不能靠弱化断言通过。当前为 macOS 环境，未复现 Windows 路径。

已请求重跑失败 job，但 GitHub 返回403：整个 workflow 仍在运行，暂不允许重跑。

Start with windowsPackagedInstanceBarrier.test.ts and windowsPackagedInstanceBarrier.ts, focusing on waitForBarrierStatus and the PowerShell cold-start/Add-Type probe. Reproduce the failing Windows CI path and compare its timing under load. Done means the probe completes reliably while the exclusive barrier, release, and later-retry assertions remain intact without weakening them.

Written by the indexing model from the issue text.