bench: the controller port and manual home harnesses

Two host harnesses for the grblHAL driver's null-sink build, in the bench
registry and the README with the others. The driver's CI runs them.

ctlport_test.py drives the controller port beside a scripted Grbl sender
that counts every ok and error it is sent, which is the only way to see a
status routed to the wrong source. 13 cases: the socket's mode; a port
jog's status going to the port with the sender's count exact and the jog
run whole under the sender's '?' polls; a port error the sender's next line
does not inherit; the sender's line canceling a fast port jog and drawing
its own ok (fast on purpose: a slow jog stops at once and would pass with no
hold at all); a sender line queued right behind the port's; the refusals;
one client, and five reconnects right after a close; the status hook across
a soft reset; the dead-man; a CR LF sender; a sender that polls the way
LightBurn does, '?' with an end of line behind it, LF and CR LF (every port
jog accepted, a 60 mm port jog run whole with the polls landing inside it,
one ok per poll, a real line still canceling a port jog); and every
operation of both sets under an open armed window with M3 modal and S500,
where the dump must hold no FIRE tick.

manual_home_test.py reads the stream dump (GFSINK_DUMP) and the attribute
log (GFSINK_ATTR_LOG), so it can say that nothing was shipped and which
current was written, and how many times. 9 cases: a manual $H ships no step
and no FIRE tick and declares the offsets with the soft limits on and Z
kept; $H refused in a cycle; $MD refused under an open armed window with
nothing written; every motion source and $X refused while released; each
energize written exactly once; the port's panel operations; both pairs of
home offsets, alone and at once; and a controller killed under a release,
whose replacement writes only 0 and 0.

Both pass against the driver's extensions tree. The poll cases fail against
the driver without its empty-line rule ("8 of 8 port jogs were refused under
a status poll"), which is the defect they were written from: it was found
on the bench reference with LightBurn connected, and the sender these
harnesses had until then polled a bare '?'.

forgetest/forgetest/bench.py

@@ -257,6 +257,23 @@ TOOLS = [
              "card's stops: the ends of the reach run, two half-steps past either end alarms. A CI harness "
              "(the grblHAL repo): needs the host-built null-sink controller, not the machine, so it is not a "
              "bench-page tool."},
+    {"id": "ctlport-test", "title": "Controller port and line multiplexer harness", "script": "ctlport_test.py",
+     "safety": "dry", "where": "host", "ported": False, "args": [],
+     "desc": "A scripted sender that counts every response, beside the controller port's one client, on the "
+             "null-sink controller: a port jog's status goes to the port and never to the sender, a port "
+             "error does not reach the sender's parser, a sender line cancels a port jog and gets its own ok "
+             "(a line queued right behind the port's included), the refusals, the single client, a CR LF "
+             "sender, a soft reset, and the client as the dead-man. A CI harness (the grblHAL repo): needs "
+             "the host-built null-sink controller, not the machine, so it is not a bench-page tool."},
+    {"id": "manual-home-test", "title": "Manual home and motor release harness", "script": "manual_home_test.py",
+     "safety": "dry", "where": "host", "ported": False, "args": [],
+     "desc": "The manual homing provider and the motor release on the null-sink controller: $H under manual "
+             "ships nothing and declares X0 Y0 with the soft limits on and Z kept; while the motors are "
+             "released every motion source is refused and ships nothing, $X and a soft reset do not unlock "
+             "it, and only $ME and a manual $H write the energize, once each; the port's panel operations "
+             "do the same with the sender's count exact. Imports its sender and port client from "
+             "ctlport_test.py. A CI harness (the grblHAL repo): needs the host-built null-sink controller, "
+             "not the machine, so it is not a bench-page tool."},
     {"id": "raster-dry", "title": "Dry top-speed raster per XY microstep mode", "script": "raster_dry.py",
      "safety": "dry", "where": "board", "ported": True,
      "args": [_arg("modes", "choice", "8 16 32", "the modes to run, in order", ["8", "16", "32", "8 16 32"])],