fix(abut): 날개벽 헌치를 내측면 기준으로 재배치

- 뒷굽 헌치 삭제
- 연직 헌치 2개(흉벽 배면, 벽체 배면)를 날개벽 내측면 모서리에 평면 삼각형 기둥으로 둠
- 저판 상면 헌치 추가: 저판 상면과 날개벽 내측면 사이의 수평 헌치 (벽체 배면 → 뒷굽 구간, 다리 0.3 m)
- 테스트 갱신 (헌치 6개, 저판 상면 헌치 범위). 전체 639건 통과, 타입 검사·빌드 통과. 브라우저 시각 확인은 미실시

Co-Authored-By: Claude Haiku 5.5 <noreply@anthropic.com>

tests/abut-scene.test.ts

@@ -21,13 +21,13 @@ const group = buildAbutGroup(model, members, wings);
 const count = (name: string) => (group.getObjectByName(name) as THREE.Group | undefined)?.children.length ?? 0;
 
 describe('교대 A1 3D 장면 (AA3·AA3b·AA3c)', () => {
-  it('has the members: 5 wall blocks, 10 parapet parts (2 per step), 1 footing, 18 piles, 2 wings, 4 haunches', () => {
+  it('has the members: 5 wall blocks, 10 parapet parts (2 per step), 1 footing, 18 piles, 2 wings, 6 haunches', () => {
     expect(count('wall')).toBe(5); // one 벽체 block per 교좌면 step (삽도)
     expect(count('parapet')).toBe(10); // per step: back strip (흉벽 배면 단차) and the 흉벽 (삽도)
     expect(count('footing')).toBe(1);
     expect(count('piles')).toBe(18);
     expect(count('wings')).toBe(4); // upper and lower part per wing
-    expect(count('haunches')).toBe(4);
+    expect(count('haunches')).toBe(6); // per wing: upper and lower 연직 헌치, and the 저판 상면 헌치
   });
 
   it('spans from the pile tip (19.295 m) up to the highest parapet end (47.18 m)', () => {

tests/abut-wings.test.ts

@@ -117,24 +117,30 @@ describe('교대 날개벽 하단 선 · 헌치 (AA3c, spec_abut §4.7)', () =>
     expect(line[2].el).toBeCloseTo(45.214, 2);
   });
 
-  it('the upper 300 × 300 haunch sits at the 흉벽 배면 (legs 0.3 m); the 뒷굽 haunch is a (t, EL) triangle with 0.3 m legs at the heel', () => {
-    expect(a2Left.haunches.map((h) => h.kind)).toEqual(['upper']);
-    const tri = a2Left.heelHaunch!;
-    expect(tri).toHaveLength(3);
-    expect(tri[0][0]).toBeCloseTo(-1.8, 6); // 뒷굽 끝 (t)
-    expect(Math.hypot(tri[1][0] - tri[0][0], tri[1][1] - tri[0][1])).toBeCloseTo(0.3, 6);
-    expect(tri[2][1]).toBeCloseTo(tri[0][1] - 0.3, 6); // leg down the 뒷굽 face
-    const [c0, c1, c2] = a2Left.haunches[0].corners;
-    expect(Math.hypot(c1.e - c0.e, c1.n - c0.n)).toBeCloseTo(0.3, 6);
-    expect(Math.hypot(c2.e - c0.e, c2.n - c0.n)).toBeCloseTo(0.3, 6);
+  it('two vertical 300 × 300 haunches at the 내측면 corners: upper at the 흉벽 배면, lower at the 벽체 배면', () => {
+    expect(a2Left.haunches.map((h) => h.kind)).toEqual(['upper', 'lower']);
+    for (const h of a2Left.haunches) {
+      const [c0, c1, c2] = h.corners;
+      expect(Math.hypot(c1.e - c0.e, c1.n - c0.n)).toBeCloseTo(0.3, 6);
+      expect(Math.hypot(c2.e - c0.e, c2.n - c0.n)).toBeCloseTo(0.3, 6);
+    }
+  });
+
+  it('the 저판 상면 haunch runs from the 벽체 배면 to the 뒷굽 on the 저판 상면; the 뒷굽 haunch is gone', () => {
+    const f = a2Left.footingHaunch!;
+    expect(f.el).toBeCloseTo(41.995, 3);
+    expect(f.dMTo).toBeGreaterThan(f.dMFrom);
+    expect((a2Left as { heelHaunch?: unknown }).heelHaunch).toBeUndefined();
   });
 
   it('upper haunch runs from the bracket top (흉벽 상단 − 0.85) to the wing top', () => {
-    const [up] = a2Left.haunches;
+    const [up, low] = a2Left.haunches;
     // The upper haunch rests on the highest point of the 브라켓 top over its footprint (the top falls along s), never below it.
     expect(up.zBottomEl).toBeGreaterThanOrEqual(46.838 - 0.85 - 1e-6);
     expect(up.zBottomEl).toBeLessThan(46.838 - 0.85 + 0.05);
     expect(up.zTopEl).toBeGreaterThan(up.zBottomEl);
+    expect(low.zBottomEl).toBeCloseTo(41.995, 3);
+    expect(low.zTopEl).toBeCloseTo(46.838 - 0.85, 2);
   });
 });