Address review findings on the CPython backend:
- CRITICAL: a model program could leave a descendant in the child's own
process group that ignores SIGTERM but releases the inherited pipes, so
the leader's `close` fired and settle() cancelled the pending SIGKILL
before it escalated — run()/dispose() returned while that child lived.
kill() now unrefs the grace timer and settle() no longer clears it, so
the SIGKILL reaches the whole group; killGroup swallows ESRCH when the
group is already gone (the normal case). Adds a real-subprocess
regression test.
- WARNING: the maxLogBytes/maxValueBytes load bound divided the frame
ceiling by 6 for escape expansion, but both budgets are metered in
already-escaped serialized bytes, so a payload occupies at most
cap+envelope on the wire. Bound is now ceiling-envelope; drop the unused
escape constant.
- Narrow the runtime.spec.ts header to "no subprocess mocks" (it mocks
node:fs.copyFileSync for staging-failure cases).
- Use full-width punctuation in the README.zh.md prose per translation
rules; re-record the pair.
9a05c0075f