chore(core): annotate remaining hardcoded timeouts

Missed in the timeouts.sh migration: brew outdated (manage/update.sh)
and hdiutil info/detach (optimize/diagnostics.sh) still had bare 8s/15s
literals. Add the same "Ns: <why>, see lib/core/timeouts.sh" inline
comment used elsewhere so the value is self-explaining without a bucket
lookup.