A test that does not hand the machine back fails

The baseline has always examined the machine after every run and recorded
what the run left behind. It did nothing else with it: the leftovers went
to the log and the evidence, and the test still reported PASS. So a check
could measure correctly, walk away with the machine in a state nobody
chose, and be recorded green.

That is how the purge fan came to be left off by the airflow check. The
leftover was not even watched, but had it been, it would have been noted
and the test would have passed anyway, and an operator would still have
met the airflow hold at their first fire.

A post-run leftover now fails the run. One the baseline put back fails it
too: the restore is the bench cleaning up after a defect, not the defect's
absence. The message names what was left.

The baseline watches the head as well as the motion side now: purge air
on, which is how the machine idles, and the lens motor at its hold current
in half step, which the lens checks and the sheet cards take and must hand
back. The airflow check proves the machine is whole rather than merely
measured: afterward the purge fan must read commanded-on and must draw
above the floor the check itself just wrote.

The pin takes forgectrl 0.1.13 (a2d73ef), which restores the idle posture
after a diagnostic, fixes the lens session's takeover flag, and gives the
setup a Download logs button, since the panel's Logs tab is unreachable
until the setup is complete.

Expect this to find things. A test that has been handing the machine back
imperfectly has been passing until now, and the first campaign under the
rule is where that shows.

forgetest/forgetest/baseline.py

@@ -65,6 +65,21 @@ FIXED_SYSFS = [
     ("head/white_led", "0"),
     ("thermal/heater_pwm", "0"),
     ("thermal/tec_on", "0"),
+    # Purge air runs continuously, as on the factory machine: the engine
+    # turns it on at start and only a listening (the quiet hold) switches
+    # it off, which puts it back on release. A check that switches it off
+    # to measure it and forgets leaves the machine one job away from an
+    # airflow hold mid-cut, judged against the floor that same check just
+    # wrote, and nothing notices until the daemon restarts: the engine's
+    # idle phase never re-applies its own duties. The airflow check did
+    # exactly that, and it reached an operator's first fire.
+    ("head/purge_air", "1"),
+    # The lens motor at rest: hold current, half step. The lens checks and
+    # the sheet cards take it to the run current in full or half step and
+    # must hand it back, or the motor sits hot and the next reference
+    # starts from a state nobody chose.
+    ("head/z_current", "1"),
+    ("head/z_mode", "1"),
 ]
 
 # The subset the GRBL controller writes at its start: checked and restored