Close the laser power model item; add the side-by-side chooser

The corner rolloff's right value is per machine (this bench settled at
1.5 against the shipped default of 2), so the commissioning item gains
a side-by-side chooser: the same corner-heavy pattern cut at several
settings, the operator picks the best by eye, Apply writes the winner -
with the dose-curve recorder as the first piece of that tool family and
its template. With that, everything the laser power model item held is
answered or homed: its conclusions live in the Laser control section
and the facts bank, its dated record in the CAMPAIGN-LOG, and the
tree-root working file is deleted per its own charter. Next work item
16 closes; the later items renumber down by one.

docs/CAMPAIGN-LOG.md

@@ -6016,6 +6016,16 @@ B5 on image 20260830200842, the generated grayscale wedge (`bench-data/gray-wedg
 
 The analog pass (A5) was cancelled by the operator's decision that ends the mode: analog fires a spot at every turn-on, low power included - the strike transient, seen at A1 as the start-of-line spots and at the corner drill as the scorch halo - and the finish comparison had already found no advantage (identical finish on acrylic). Density is the only product model from here; the analog rendering survives only as the host harness's conservatism reference (the mask rule), selectable only in the null-sink build.
 
+### The dose curve, the corner rolloff, and the recorder's first live fit, 2026-08-31
+
+Shipped across images 20260831003319 to 20260831021059 (pins forgectrl fac30a4, grblhal 06965b6): S commands a light fraction through `laser_dose_curve` (bench-default compiled in), `laser_corner_gamma` (default 2) bends the M4 rolloff so corners are starved rather than proportional - built after the first curved corner job over-burned, and reached driver-only after three instrumented probes showed the programmed S is unreachable from the compute path in laser mode (the driver now mirrors the parser's S into an atomic each poll pass) - and the dose-curve recorder streams its own ladder from one panel press, absolute from X0 Y0, gated on the published sender flag. Two defects found by their own gates on the way: forgectrl's -Werror CI caught a literal NUL byte a patching tool had written into a char constant, and the recorder's first live fit refused cleanly ("1 discharge segments, the ladder has 7 rungs") because the inter-rung rapids were darker than a second only - a G4 P2 dwell per rung fixed it. The status echo also gained a sub-second negative-age tolerance after a millisecond-rounding coin flip in its host test.
+
+The first live recording on image 20260831021059 then fit all seven rungs and the operator applied it: this machine's own curve is 10:0.52, 20:2.63, 30:8.18, 45:23.15, 60:40.66, 80:54.76, 100:100 - within a few points of the bench-default at every rung, the 80 percent rung reading 55 percent of full light where the depth witnesses had said about half. The floor key was restored by the recorder as designed. E4 and E5 of the working file are bench-proven; the corner look at the default rolloff is the file's last open item.
+
+### The laser power model closes; the working file retires, 2026-08-31
+
+The corner look on image 20260831021059 with the machine's own recorded curve: the operator lowered the corner rolloff from the default 2 to 1.5 and expects to go lower - the knob works, its right value is per machine, and the commissioning item gains a side-by-side chooser (the same pattern cut at several settings, the operator picks by eye, Apply writes the winner) as the tool for it. With that, every question the tree-root working file `LASER_DUTY_WORK.md` held is answered or homed: the model decision (density only), the measured curves, the floors, the switch's rise and removal, the rolloff, the recorder, and the raster proofs. Its conclusions live in BRINGUP's "Laser control (GRBL mode)" and the facts bank, its dated record in this log, and the file is deleted per its own charter. BRINGUP's "Next work" item 16 (the laser power model) closes and the later items renumber down by one (17 to 23 become 16 to 22).
+
 ## Reference notes
 
 ### Head-IRQ source validation — the beam-emission hypothesis