[codex] bound deadline process cleanup

[hqhq1025]

What changed

• bound buffered stdout/stderr replay to 60 seconds and mark replay processes for scope cleanup
• bound TERM and KILL cleanup commands to 10 seconds each
• let a successful KILL settle the deadline even if the TERM transport failed
• add regressions for blocked output replay and Claude Code cancellation cleanup
• document timeout settlement semantics

Root cause

When a pinned CLI reached its task-native deadline, the command wrapper could block replaying buffered output into an abandoned Docker exec pipe. After that was bounded, Claude Code still exposed a second failure mode: the TERM cleanup transport could hang indefinitely. Harbor remained in n_running_trials=1, never invoked the verifier, and the outer watchdog eventually recorded a false infrastructure failure.

The affected run showed Claude output stopping exactly at the task-native deadline while Harbor stayed alive for the full agent + verifier + teardown watchdog window.

Behavior

TERM and KILL remain ordered. If TERM transport fails but KILL succeeds, the original budget-exhausted cancellation propagates and Harbor can grade the deadline workspace. If KILL also fails, cleanup still fails closed as infrastructure because the workspace cannot be proven frozen.

Validation

• node --test packages/headless/dist/__tests__/harbor-adapter.test.js
• local: 21 passed, 5 environment-dependent skips
• Harbor 0.13.2 isolated worktree: 25 passed, 1 clean-worktree-only skip
• python3 -m py_compile packages/headless/harbor/process_scope.py
• biome check and git diff --check

[jackwener]

感谢补上 process cleanup deadline 这一重要的 lifecycle invariant。

这个 patch 的 3 个变更文件全部位于已经删除的 packages/headless。#2605 已将公开 Eval 完整迁移到 packages/eval，并要求执行统一通过 shared executor 与 Runtime Host。对应的 bounded cleanup 也已经在 current packages/eval/harbor/relay_agent.py 中由 TERM/KILL deadline 实现，分别覆盖 trial/process-group cleanup 路径。

因此旧 Headless patch 已无法也无需合入，关闭这个已迁移完成的 PR。如果 current Eval cleanup 仍存在一个具体漏口，欢迎直接针对 packages/eval 的现有 owner 提一个聚焦修复。

Thank you for tightening this lifecycle boundary. packages/headless was retired by #2605, and current packages/eval/harbor/relay_agent.py now owns bounded TERM/KILL cleanup. Since all files changed here belong to the removed Headless implementation and the invariant has moved to Eval, I am closing this PR as superseded.