Read a timeout Sending an Ignored or Stopping Signal as No Bound #2316

Problem

The wait-loop check in host-setup/agent-safety/claude/gh-write-guard.py reads a timeout sending signal 0 as no bound, since that signal reaches no process. Other signals whose default action is to ignore or stop the child bound nothing either: CONT, CHLD, URG, and WINCH are ignored by default, and STOP, TSTP, TTIN, and TTOU stop the child rather than end it. Constructed example, read as bounded:

timeout -s CONT 900 bash -c 'until [ -f x ]; do sleep 60; done'

Without a -k, the timeout sends the signal at the deadline and goes on waiting for a child that keeps running or sits stopped.

Done looks like

The check reads a timeout sending any of those signals, by name or number, as no bound unless a -k in the duration form follows, with self-test rows and README requirement 7 updated.

Carried as an unfiled follow-up through the auto-1634 lane (#2072), which settled the signal-0 case in #2117.