Revert "Reapply "fix(abut): 날개벽의 연직 헌치 삭제""

This reverts commit 61ef001034.

tests/abut-wings.test.ts

@@ -117,6 +117,15 @@ describe('교대 날개벽 하단 선 · 헌치 (AA3c, spec_abut §4.7)', () =>
     expect(line[2].el).toBeCloseTo(45.214, 2);
   });
 
+  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);
@@ -124,6 +133,15 @@ describe('교대 날개벽 하단 선 · 헌치 (AA3c, spec_abut §4.7)', () =>
     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, 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);
+  });
 });
 
 describe('날개벽 수평 단 (QA-12 초안 적용, spec_abut §4.7)', () => {