Pure units module: bdft = sqft × thickness_in (no /12), half-up
rounding for sqft/bdft/price, length to nearest 1/8". Property
checks for monotonicity in thickness and sqft.
TDD: red evidence in test-results/tv3-tv10-red.txt, then minimum impl.
Results:
TV-3 | pass | test-results/tv3-tv10-green.txt
TV-10 | pass | test-results/tv3-tv10-green.txt
