Addresses the review's two code warnings and one suggestion:
- die_if_cpu_exhausted now restores SIG_DFL BEFORE unblocking SIGXCPU: a program
that installed a custom handler AND masked the signal would otherwise have
that pending handler run at the unblock (in model code, re-masking or raising)
and escape the re-raise; with SIG_DFL first the pending signal kills inside
the kernel with no bytecode window. A trap+mask combined regression test pins
it (the mask-only case was already covered).
- The constructor rejects budgets too small to honor: maxLogBytes must fit the
truncation marker plus the serialized outer-array envelope (floor 64), and
maxValueBytes must at least represent the smallest JSON completion (floor 4,
matching the worker backend). The exact-limit test moves to the 64 floor and
a rejection test pins the floors.
- The pthread_sigmask None-guard comment cites the real rationale (defensive
against stripped CPython builds; win32 is refused at construction), not the
unreachable Windows path.
4a8c49f78c