A cron tick can fire while the gateway is tearing down (SIGTERM from
`hermes update` / `hermes gateway stop` / systemd restart, or an OOM-kill).
Once the interpreter is finalizing, `concurrent.futures` refuses new work
with `RuntimeError: cannot schedule new futures after interpreter shutdown`
and asyncio's default executor is gone, so the cron delivery and dispatch
paths crash the tick and spray a traceback into errors.log on every
restart-race. Telegram/live-adapter deliveries surface it as
"Telegram send failed: ... cannot schedule new futures after interpreter
shutdown".
Add `_interpreter_shutting_down()` and consult it at the scheduling sites:
- the standalone delivery path (`asyncio.run` + the fresh-pool fallback),
- the tick dispatch (`_submit_with_guard` `pool.submit`).
When finalizing, skip gracefully with a warning instead of raising; the job
stays due and fires on the next healthy tick. The helper also matches the
RuntimeError text as a fallback, since the concurrent.futures global flag can
be set a hair before `sys.is_finalizing()` flips.
Fixes#58720. Also addresses the cron paths in #55924.
8aab8be50c