cooling.fans-quiet-after-motion sat silent for four minutes on the bench
and then failed. Its idle reference was the tachs one second after the
baseline saw the engine go idle, while the previous test's fans were
still coasting at the cooldown level (exhaust 5030 rpm against a true
idle of 0), so it then waited for the fans to come back UP to a level
that was never idle. The cooldown wait printed nothing while it waited.
The reference now needs the engine idle, the idle duty applied to both
fan channels, and three consecutive tach samples that agree; the pass
condition is the idle duty back and the tachs at or below that reference
(lower is quieter, never a fault); M8 must visibly raise the duty; and
every sample of both waits is logged with the phase and the duty, so the
run pane shows the fans coasting down rather than a hang.
Proof: tests/test_cooling_suite.py replays the test under the real
Context against a scripted machine (fake forgectrl, fake sysfs duties,
fake Grbl port): an idle machine passes, the bench case (fans coasting
when the test starts) passes with the reference taken after the coast,
fans left on fail with the reference in the message, and a reference
that never settles fails before anything is jogged. No catalog
consequence beyond the suite module's own hash.
