The drawer is 345mm long but the printer maxes out at 340mm, so dialed
the length back to fit. Also added the 3MF build target to the Makefile
so this baseplate gets exported alongside the pegboard shelves.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

The drawer length was hardcoded as 8*42=336mm but the actual interior
is 345mm. Now using min_size_mm for both axes so the baseplate pads
out to fill the real drawer dimensions (345x240mm) while still fitting
8 grid units lengthwise.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

The SCAD file already supported grid_y=3 but we weren't building any of
them. Now generating all 8 widths at depth 3 alongside the existing
depth 1 and 2 variants.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Gussets on every grid boundary now instead of every other, and the outer
gussets get trimmed with a quarter-cylinder cut to match the baseplate's
corner radius so they don't poke out past the rounded edges.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

First 1x1 test print showed the hooks and pegs were way too long, the
15° tilt was more aggressive than expected, and the baseplate was
colliding with the backplate after rotation. Shortened j-hooks and
bottom pegs by about half, dialed the tilt back to 10°, and added a
forward clearance offset so the baseplate clears the backplate wall.
Reworked the gusset geometry to follow the actual shelf underside angle
and tuck inside the baseplate radius.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>