feat(abut): 교대 벽체·흉벽 삽도와 수축줄눈·흉벽 Level 입력 추가

- 벽체·흉벽 개략 단면 SVG(src/view/abut-section-svg.ts)를 형상 카드 맨 위에 추가. 치수 글자는 카드 입력값을 mm로 표시하고, 값을 바꾸면 다시 그림
- 형상 입력에 수축줄눈 개수(정수 0 이상)와 흉벽 상단 Level 좌·우(450·995, 계산 미사용·QA-4)를 추가. 기하 계산에는 쓰지 않음
- 테스트 619건 통과, 타입 검사·빌드 통과

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

src/main.ts

@@ -9,7 +9,8 @@ import { buildAbut } from './core/abut/geometry';
 import { structureOrder } from './core/abut/order';
 import { ABUT_DETAIL_LABELS, abutInputRows, abutSummaryRows } from './core/abut/summary';
 import { applyAbutEdit, applyBearingEdit, applyShapeEdit, ABUT_EDIT_FIELDS, SHAPE_EDIT_FIELDS, restoreAbutDefault, setWingForm } from './core/abut/edit';
-import { ABUT_SHAPE_DEFAULT } from './core/abut/shape';
+import { ABUT_SHAPE_DEFAULT, resolveShape } from './core/abut/shape';
+import { abutSectionSvg } from './view/abut-section-svg';
 import type { WingForm } from './core/abut/geometry';
 import { buildMembers } from './core/abut/members';
 import { buildWings } from './core/abut/wings';
@@ -645,6 +646,10 @@ function fillAbutSlot(slot: (typeof ABUT_SLOTS)[keyof typeof ABUT_SLOTS], rec: A
   basic.replaceChildren();
   bearings.replaceChildren();
   shape.replaceChildren();
+  // 삽도 (벽체·흉벽 개략 단면): the values it names are the card's values, so the drawing follows each change.
+  const drawing = el('div', undefined, 'abut-section');
+  drawing.innerHTML = abutSectionSvg(resolveShape(rec.shape), { ...ABUT_SHAPE_DEFAULT, ...(rec.shape ?? {}) });
+  shape.append(drawing);
   msg.textContent = '';
   const apply = (next: AbutRecord) => {
     state.abutments = state.abutments.map((a) => (a.name === next.name ? next : a));