tray_test.py and motion.tray: the crumb tray's mode on the null-sink controller and on the machine

- scripts/bench/tray_test.py, run by the driver's CI: M103 P1 and P0
  move Z and its envelope by tray_offset_mm on the lens step grid, tell
  the sender, write and remove the marker beside the shared config, and
  ship no step; a missing P, P2, P0.5, P-1, and an axis word are errors
  that change nothing; the switch behind a move waits for the move; the
  port's tray op with a sender connected, its count exact, refused out of
  form, during a program, and at a package's M-code; the mode across a
  soft reset and a killed controller, a start over the marker taking the
  lens reference in the tray-out frame; the offset's range; an
  unreferenced lens; a camera home in both modes handing the runner the
  same park. The kernel-idle half of the barrier needs the pulse device:
  a null sink is always idle.
- scripts/bench/ctlport_test.py: the dark case carries tray out and in
  under an open armed window.
- forgetest: motion.tray in its own module, suite/tray.py, so no other
  test's fingerprint moves. It switches the mode both ways through the
  panel's route and through M103 from a Grbl client and judges each
  switch: /status's mode, Z, and reach moved by the offset's grid, the
  port's state, the marker, the reference and its source unchanged, the
  client told, the kernel's counters unmoved. A jog to the Z the lens
  read before a switch is refused in the other mode and taken back in
  the mode found; a setup card started with the tray out is refused in
  the operator's words; the panel page carries the switch. The mode goes
  back as found in a finally. It does not restart the controller, which
  would drop the X and Y reference: persistence is tray_test.py's.
- The bench registry and README list tray_test.py.

Proof: tray_test.py ALL PASS against the driver with the mode, and six
driver copies each missing one part of it fail. The driver's whole CI
harness list passes. The forgetest unit suite: 500 tests OK. The
coverage lint over the working trees: nothing uncovered, 126 tests. On
the bench reference, with the binaries hot-deployed on the fx18 image:
motion.tray PASS, and FAIL against the driver whose anchor lost its
source word on the second switch.

Acceptance. motion.tray is new; the suite and bench files are in no
other test's fingerprint.

scripts/bench/README.md

@@ -36,6 +36,7 @@ page's takeover does that; from a host, stop them first.
 | `ctlport_test.py` | Host-side controller port and line-multiplexer harness (null-sink controller): a scripted sender that counts every `ok` and `error` runs beside the port's one client on `grbl.ctl`. 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), plus the refusals, the single client, a CR LF sender, a soft reset, and the client as the dead-man. `python3 ctlport_test.py <grblHAL_glowforge>`. |
 | `cool_report_test.py` | Host-side cooling report harness (null-sink controller, a stand-in for forgectrl's listener on `FORGECTRL_PORT`): every `POST /cool/state` carries the secret the supervisor hands the controller at its spawn (`GF_REPORT_SECRET`) as `X-ForgeFIRM-Report`; with no secret the header is absent; a value that is not 32 hex digits, a CR LF with a header behind it included, never reaches the wire; and the homing runner the controller starts is handed the secret (it reports in the controller's place during a gfcloud `$H`), and none when the controller has none or a malformed one. `python3 cool_report_test.py <grblHAL_glowforge>`. |
 | `manual_home_test.py` | Host-side manual homing and motor release harness (null-sink controller, `GFSINK_DUMP` and `GFSINK_ATTR_LOG`): `$H` under `homing_mode = manual` ships nothing and declares X0 Y0, and with a manual home offset declares minus it and jogs dark to the origin before it answers, a jog cancel ending the move short; while the motors are released (`$MD`) every motion source is refused and ships nothing, `$X` and a soft reset do not unlock it, and only `$ME` and a manual `$H` write the energize. Imports its sender and port client from `ctlport_test.py`. `python3 manual_home_test.py <grblHAL_glowforge>`. |
+| `tray_test.py` | Host-side crumb tray harness (null-sink controller, `GFSINK_DUMP`): `M103 P1` and `P0` move Z and its envelope by `tray_offset_mm` on the lens step grid, tell the sender, write and remove the `tray.out` marker beside the shared config, and ship no step; the errors of `M103`; the switch waits for the move before it; the port's `tray` op and its refusals; the mode across a soft reset and a controller restart; the offset's range; an unreferenced lens; a camera home in both modes. Imports its sender and port client from `ctlport_test.py`. `python3 tray_test.py <grblHAL_glowforge>`. |
 | `live_fire_drills.py` | **LIVE LASER** drills, on the board (the bench page) or from a LAN host (`GF_HOST`): `live_fire_drills.py <drill> [S] [F]` - `witness` (emission witness, lid-IR peaks vs the ambient baseline, HV current, job-based disarm on M2), `hold` (disarm grace in Hold), `faultpos` (armed job refuses a stale origin after an underrun), `ircut` (lid-IR characterization cut at S/F), `pthresh` (laser power-threshold ladder: 13 constant-power rungs from 2 % to 30 % of full on scrap; the lowest rung that marks is the tube's striking threshold and reads directly as the `$35` value - requires `$35` = 0 for the run), `dladder` (density ladder at a chosen base period), `pcurve` (laser performance-curve ladder: one 100 mm line per level at 10 mm/s under M3, the laser off between rungs and a mid-ladder rung repeated at the end; reads `pic/hv_current` and the head thermopile `head/beam_detect_analog` (a scatter detector in the beam path upstream of the final mirror, so it sees the beam, not the material) from sysfs at ~25 Hz on the board, brackets each rung on the controller's Run/Idle states, and reports per rung the current with a clipped-at-1023 flag, the thermopile delta over its laser-off baseline and in-line drift, then the normalized curve, monotonicity, a line fit with its threshold intercept and the repeat-rung drift; JSON record with the raw trace in the bench data directory; rungs follow `laser_power_model`, a comma list overrides; a curve measurement wants `$35` = 0), `dpatch [F] [pitch] [length]` (depth witness for the density dose curve: two rows of small serpentine-filled patches, row A CW at feeds giving relative doses 1.0 to 0.25 of the reference feed, row B at the reference feed at 100/80/60/45/30 % density; the operator matches each row-B patch to the row-A patch of equal depth, which reads the density's light fraction off the material beside the thermopile's prediction; JSON record), `m4feeds [S] [F1] [F2]` (the density time base across feeds: one out-and-back line pair per feed at the same S under M4 density, one armed run; the operator reads within-line evenness and reversal darkness at both feeds - M4's velocity scaling is what holds dose per mm through the accel), `m4corner [S] [F]` (M4 velocity-scaled power into corners: a corner-heavy vector pattern at 30 % under M4 density, one armed run; the operator confirms every commanded segment marks - the floor makes a dropout unreachable - and the drill asserts the arm report, one discharge window and dark after), `m5dark` (the rapids after an M5 ship dark: one 20 mm line at M3 S400, M5, dwell, rapid back, dwell, rapid forward; PASS when the 25 Hz current trace shows one discharge segment and reads dark after the M5 and `laser_on_sampled` never re-lights; the catalog's `laser.m5-rapid-dark` is its port), `flowload` (cooling under laser load, one armed run per invocation, the conf keys it writes put back at the end, the pump never commanded off: `t1` reproduces the flow-check trip with the check on at its defaults and two 30 x 4 mm CW fills at F1500 starting on the press with no dark dwell, and reports the engine's rise/dT verdict beside the 25 Hz trace of both coolant sensors, the current, the digital witness and the heater output in 5 s bins across the window, with the shape at fire start; `t2 <secs> [pct]` runs with the check off and one fill of about `secs` lit seconds at CW or at `pct` density, and reports the lag to each sensor, the rise per raw-second of `hv_current` and what a full 50 s window would add against the 1.6 C margin; `fit` fits rise against dose over every t2 record; JSON records), `expstop` (armed kill on the expected-stop path; needs the panel token - `GF_TOKEN`, or the board's token file) and `ctrlstart` (the separate controller restart after it). Every drill waits for the operator's physical arm press; eye protection, fire watch, extinguisher, and exhaust are mandatory. |
 | `pacing_test.py` | Protocol-loop pacing check (runs on the board, dry motion): idle and parked-in-Hold states are coarse-paced, active motion is tight-paced, and a feed-hold/resume mid-move preserves position with no feeder starve. |
 | `planner_blocks_test.py` | Host-side planner buffer depth harness (null-sink controller): `$398` written to 400 and to 1000, the controller restarted on the same settings store each time, and it must answer on the port, report the depth in its status report and run a move. A byte-wide ring index once made 255 blocks or more spin the start. Runs in the grblHAL repo's CI. |