forgetest: the operator proves presence at the machine, the bench presses

A live test asked a person to click Ready on a page and then make
timing-critical presses in the middle of a burning cut. That is how
tonight's pause test became unanswerable: the actuator had dropped off
the network, the harness fell back to the operator without saying so,
and afterwards nobody could tell a second press from the machine
resuming on its own.

Where an actuator is up and wired to the button, the ready gate now
takes a press on the machine's own button as the presence check, and the
actuator performs every press in that test. The button does nothing at
Idle, so the press is only a presence check, and the gate waits for the
release so it is never read as the arm press. With no actuator the
operator does the presses and answers on the page, as before.

An actuator lost after that takeover is now said out loud, in the log
and in the evidence, instead of quietly becoming a person's press.

The live-fire cue was four lines of machine-shaped prose. It is now what
a person needs: protection, exhaust, extinguisher, scrap, lid.

forgetest/forgetest/suite/laser.py

@@ -60,10 +60,8 @@ def _grbl_settings(lines):
                 pass
     return vals
 
-ARM_CUE = ("LIVE FIRE. Eye protection on, exhaust running, fire watch and extinguisher in reach, "
-           "scrap under the head with room to move (%s), lid closed. On Ready the job starts: "
-           "the white button lights and the stream waits for your press of the physical arm "
-           "button; the machine fires only after that press.")
+ARM_CUE = ("LIVE FIRE. Eye protection on. Exhaust on. Extinguisher in reach. "
+           "Put scrap under the head with %s clear, and close the lid.")
 
 # The beam detector's emission signature: this much over its pre-fire
 # level while the beam is on (bench: ~1834 idle, 2600-2890 at S300/S400).