feat(abut): ③ 교대 반투명 보기 · 교대 저판 전용 fck

- ③ 철근배근에서 교대 부재·지반도 교각처럼 반투명(0.5, 깊이 쓰기 끔). setRebarViewOn으로 공통화, 끄면 원래 불투명도 복원(지반 0.35 유지)
- 교대 저판 fck(abutFooting, 기본 27)를 교각 기초 fck와 분리. ② 확대기초·말뚝 카드에 입력, ③ 저판 배근·이음 길이에 반영
- 테스트 713개 통과

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

src/main.ts

@@ -109,7 +109,7 @@ import { choose, defaultSummary, isSelectable, SHAPE_GROUPS, UNDEFINED_REASON, t
 import { parseProject, SCHEMA_VERSION, serializeProject, type ProjectFile, type ProjectInfo } from './core/project';
 import { clearBackup, readBackup, writeBackup, type Backup } from './view/backup';
 import type { Issue, PierInput, PierType, StrataRow } from './core/types';
-import { buildPierScene, setRebarView, viewPosition, type PartName, type PierScene, type ViewKind } from './view/scene';
+import { buildPierScene, setRebarView, setRebarViewOn, viewPosition, type PartName, type PierScene, type ViewKind } from './view/scene';
 import { buildAllPiers, type AllPiers } from './view/all-piers';
 import { buildTerrainMapGroup, disposeTerrainMapGroup, setTerrainMapMode } from './view/terrain-map';
 
@@ -631,6 +631,7 @@ function setupScene(): void {
           const member = group.getObjectByName(name);
           if (member) member.visible = on;
         }
+        setRebarViewOn(group, state.stage === 'rebar');
         abutGroups.push(group);
         abutGroupByName.set(rec.name, group);
         world.add(group);
@@ -1486,6 +1487,18 @@ function fillAbutFootingExtras(
   auto('길이 (자동)', `${L.toFixed(3)} m`, '교좌면 길이 (skew)');
   auto('말뚝 길이', `${Math.round(rec.pileLengthMm)} mm`, '① 기본 정보에서 수정');
   auto('선단 EL (자동)', built.members.pileBottomEl === undefined ? '—' : `${built.members.pileBottomEl.toFixed(3)} m`, '= 기초 하단 − 말뚝 길이');
+  // 교대 저판 fck: 교각 기초 fck와 따로 둔다 (사용자 결정 2026-11-04). 비우면 기본값으로 돌아간다.
+  const fckId = idOf('fck');
+  const fckLab = el('label', 'fck (MPa)');
+  fckLab.htmlFor = fckId;
+  const fckIn = el('input');
+  fckIn.id = fckId;
+  fckIn.type = 'number';
+  fckIn.step = 'any';
+  fckIn.value = String(state.fckByMember.abutFooting ?? state.material.fck);
+  if (fckChanged(state.fckByMember, 'abutFooting')) fckIn.classList.add('changed-input');
+  fckIn.addEventListener('change', () => setMemberFck('abutFooting', fckIn.value));
+  box.append(fckLab, fckIn, el('span', `기본 ${IMPORTED_FCK.abutFooting} · 교각 기초와 별도 · 배근에만 반영`, 'muted small'));
   // 열 위치 (배면부터): "650 · 2000 · 1300 · 650". The last one (전면 연단) follows from the 폭.
   const id = idOf('pile-rows');
   const lab = el('label', '열 위치 · 배면부터 (mm)');
@@ -2549,6 +2562,7 @@ function setStage(stage: Stage): void {
   // Entering or leaving ② changes which objects are drawn (visibility.ts), so the scene is rebuilt then.
   if ((allPiers !== null) !== multiSceneOn() || stage === 'plan' || previous === 'plan') setupScene();
   if (state.scene) setRebarView(state.scene, stage === 'rebar');
+  for (const g of abutGroups) setRebarViewOn(g, stage === 'rebar');
   $<HTMLElement>('view-shape').hidden = stage !== 'shape';
   $<HTMLElement>('view-plan').hidden = stage !== 'plan';
   $<HTMLElement>('view-rebar').hidden = stage !== 'rebar';
@@ -3083,7 +3097,7 @@ function abutFootingBuilt(rec: AbutRecord): { geom: AbutFootingGeom; result: Abu
     const model = buildAbut(toAbutInput(rec));
     const members = buildMembers(model, { bottomEl: rec.foundationBottomEl, pileLengthMm: rec.pileLengthMm }, rec.shape);
     const geom = abutFootingGeom(model.length, members.shape, skewAngle(rec.skewDeg));
-    const result = abutFootingRebar(geom, rec.rebar?.footing, materialFor(state.material, state.fckByMember, 'footing'), rec.name);
+    const result = abutFootingRebar(geom, rec.rebar?.footing, materialFor(state.material, state.fckByMember, 'abutFooting'), rec.name);
     return { geom, result, skewK: abutSkewK(model) };
   } catch {
     return null;
@@ -3273,7 +3287,7 @@ function fillAbutFootingRebarCard(box: HTMLDivElement, rec: AbutRecord, built: {
     grid2.append(cell);
   }
   // 자동 값.
-  const fck = materialFor(state.material, state.fckByMember, 'footing').fck;
+  const fck = materialFor(state.material, state.fckByMember, 'abutFooting').fck;
   const fy = (size: string) => fyOf(state.material, size);
   const auto = (label: string, value: string) => {
     const cell = el('div', undefined, 'abut-rebar-auto');