PHLEGM v8 - Checkpoint 73 - CHOP icon physical minimum thickness

Every CHOP icon model must have at least 5% of its largest declared SIZE-MM
axis as the local thickness of any connected SOLID material span. This is
physical/model-space thickness, not minimum on-screen pixels or a shadow line.
It applies to thin folder tabs/panels, document sheets, cartridge features,
and other icon materials on all three axes.

The data-driven MIN-THICKNESS|5|PERCENT-MAX rule is enforced at MAIN bake
using the final accepted CHOP voxel reconstruction resolution. The guard
checks every nonempty axial solid run, including pockets revealed by RECESS,
without filling negative-space holes. A failing model reports its identity,
axis, actual millimeters and required millimeters, rather than displaying
a geometry that violates the thickness constraint.

The following physical SIZE-MM models were corrected while keeping their
original projection masks, cutouts, colors, animation, and viewport rules:
  back       42 x 34 x 17 mm   (rear panel and recessed details)
  folder     42 x 34 x 12 mm   (folder thickness)
  document   30 x 38 x 4 mm    (page thickness)
  cartridge  98 x 80 x 13 mm   (thin Y-axis features)
  console    33 x 25 x 5.5 mm  (console thickness)

Other icons already meet the 5% rule and retain their original SIZE-MM.
The mesh-fidelity diagnostic is generic to chop.lib, but icon constraints
are applied only when baking icon models; CHR glyph meshes are unchanged.
The regression in tests/chop-selftest.bas checks the configured threshold,
valid geometry and rejection of a deliberately under-thick model.

Native FreeBASIC compile/runtime: verify with local fbc; the compiler is not
preinstalled in this generation environment. The blueprint geometry and
minimum-run lengths were separately checked at source and accepted fidelity.
