Key the painted checkerboard out of the provided gem art via an
edge-connected flood fill (8-conn, light+desaturated predicate) so the
gems' interior specular highlights are preserved, then slice the 6 gems
by alpha bbox, premultiply-resize each to fit 108x108, and center one
per 128x128 transparent cell in index order (red, orange, yellow,
green, blue, purple).
Stand up build.sx (macos + ios/ios-sim targets, bundle id
co.swipelab.m3te, output sx-out/ios/M3te.app, assets dir) and a minimal
main.sx that brings up the platform (UIKit+Metal on iOS, SDL3+GL on
macOS) and renders a solid-clear frame. Add assets/ and goldens/
directories and a .gitignore for build artifacts.
Modeled on game/build.sx and game/main.sx; modules resolve from the
compiler binary with no -L flag.
