fix: /update now drains active agents before gateway exit

[mahdiwafy]

Summary

/update spawned the update helper via setsid but did NOT call request_restart(), so the gateway exited without running the drain phase (active_at_start=0, drain took 0.00s). This killed active cron jobs and tool subprocesses mid-work.

A production incident with the Daily family briefing during /update showed the more severe failure mode: the cron job started, then never logged completion or delivery.

Fix

Call request_restart() after spawning the update helper, same as /restart does. This triggers stop() -> _drain_active_agents() with the configured restart_drain_timeout, giving in-flight work a graceful drain window before the gateway process exits.

Comparison: /restart vs /update (before fix)

	/restart	/update (before)	/update (after)
Spawn detached helper	yes	yes	yes
request_restart()	yes	no	yes
stop() -> _drain_active_agents()	yes	no	yes
Drain timeout	restart_drain_timeout	none	restart_drain_timeout

Closes #60432

[teknium1]

Thanks for the focused investigation and the clear comparison with /restart.

Automated hermes-sweeper review found that the behavioral guarantee is already present on current main:

• hermes_cli/main.py:10346 restarts gateways after an update; its service and manual-gateway paths use _graceful_restart_via_sigusr1(...) with the drain budget (hermes_cli/main.py:10628, hermes_cli/main.py:10884).
• gateway/run.py:5658 now includes scheduler-owned in-flight cron jobs in _drain_active_agents(), so cron-only work no longer produces an immediate zero-active drain.
• gateway/run.py:8048 marks jobs interrupted after forced subprocess cleanup, preventing the false-success outcome reported in /update bypasses drain and interrupts in-flight cron tool work #60432.
• Merged PR fix(gateway,cron): make shutdown drain see in-flight cron work (#60432) #60711 (ecc6725855280b4da7181c12bf930d95c7ae9a8d) added this implementation and tests/gateway/test_update_cron_drain.py coverage. The /update bypasses drain and interrupts in-flight cron tool work #60432 maintainer resolution links that salvage.

Closing as implemented on main.