fix(runtime-host): arm process lifecycle before readiness

[M4n5ter]

English

Summary

• install Runtime Host termination and disconnect handlers before a child process publishes readiness
• make execution-host cleanup failures print their underlying error instead of reporting only exit code 1
• cover the readiness ordering and listener cleanup contract with a focused regression test

Root cause

The test Host fixtures published their ready IPC message before entering the process lifecycle helper. A parent that stopped the child immediately after readiness could therefore deliver SIGTERM before the child installed its graceful-shutdown handler, producing intermittent CI failures in otherwise unrelated pull requests.

Validation

• npm --workspace @maka/runtime-host run typecheck
• npx biome lint on all changed files
• full Runtime Host test suite: 416 passed, 0 failed

中文

概要

• 在子进程发布就绪状态前安装 Runtime Host 的终止和断连处理器
• 在 execution-host 清理失败时输出底层异常，避免只报告退出码 1
• 使用聚焦的回归测试覆盖就绪顺序与监听器清理契约

根因

测试 Host fixture 在进入进程生命周期辅助函数之前就发布了 ready IPC 消息。父进程若在收到就绪消息后立即停止子进程，可能会在子进程安装优雅关闭处理器之前发送 SIGTERM，从而使无关 PR 的 CI 间歇失败。

验证

• npm --workspace @maka/runtime-host run typecheck
• 对全部改动文件运行 npx biome lint
• 完整 Runtime Host 测试套件：416 通过，0 失败