kernel/abutment.rs: - 흉벽(breast wall): X=횡단(bw_w), Y=높이(bw_h), Z=두께(bw_t) — 올바른 방향 - 기초(footing): X=횡단(ft_w), Y=두께(ft_t), Z=경간방향(ft_l) - 날개벽(wing wall): ±X 방향으로 연장 viewer/lib.rs: unused imports 제거 (경고 해소) Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>