Follow-up to the salvaged restart-wait commits:
- A drain or cron timeout of .inf now means "wait indefinitely" instead of
an OverflowError from the integer stop envelope, which crashed
`hermes gateway restart` and made `hermes update` silently fall back to
its 45s floor. The fleet "draining (up to Ns)" lines and the drain
progress report format the budget instead of int()-ing it, so an
unbounded wait no longer crashes them either (it did on main too).
- cron_drain_timeout is required: a 0.0 default meant "cron opted out",
the under-budget this fix exists to remove.
- Docstrings describe what the budget actually covers (PID exit, not
replacement startup).
- Tests assert the observer outlasts after-turn + the supervisor stop
envelope and that configured cron reaches the CLI wait, instead of
re-deriving the formula; the negative wording assertion on the pending
footer is dropped (change-detector).
8afaab3703