computeTileLayout and tileGridCapacity took minTileW / minTileH, defaulted
to TILE_MIN_W / TILE_MIN_H, and no caller or test ever passed them. The
parameters are gone and both read the constants; the spec's signature line
says so.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>