feat(rebar): rebar strength per 규격 prefix as inputs on ③ (D SD300, H SD400, S SD500)

fyH and fyS become a grade per prefix (D · H · S), chosen from SD300 · SD400 · SD500. The defaults are the P1 values, so
the P1 results do not change. Each bar takes its grade from its 규격 (fyOf). The 철근표 has a 강도 column. Older files
that stored fyH / fyS are read into the grade map. Only fck is still an assumed value (I02). Approved 2026-10-23.

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

src/core/rebar/summary.ts

@@ -4,7 +4,7 @@ import { bottomPiece, topBarLength, widthLayout } from './coping-main';
 import { shearBars, shearBarsMulti, copingSideBars, SIDE_HOOK_LEG, c14Bars, c14Length, stairBars, stepDevLength, undersideAt, shearULength, capLength, PIECES_PER_POSITION } from './coping';
 import { columnRebar, COLUMN_P1 } from './column';
 import { bottomBars, crossBars, sideBars, assemblyBars, shearB9 } from './footing';
-import { DEFAULT_MATERIAL, FckByMember, isAssumedMaterial, Material, materialFor, splitPieces } from './common';
+import { DEFAULT_MATERIAL, FckByMember, fyOf, isAssumedMaterial, Material, materialFor, splitPieces } from './common';
 
 /** 근거 badge (spec §6.1): where the value comes from. */
 export type Basis = 'input' | 'default' | 'calc' | 'assumed';
@@ -126,7 +126,7 @@ export function rebarSummary(
   // The I02 note stays while the common values are the assumed ones, unless every fck-bearing member has its own fck.
   const ownFck = (['column', 'coping', 'footing'] as const).every((k) => byMember[k] !== undefined);
   if (isAssumedMaterial(common) && !ownFck) {
-    warnings.push({ code: 'I02', message: `fck ${common.fck} MPa · fy ${common.fyH} / ${common.fyS} MPa는 가정값입니다. 정착·이음 길이에 반영됩니다. 공통 설정에서 확인하세요.`, target: 'common' });
+    warnings.push({ code: 'I02', message: `fck ${common.fck} MPa는 가정값입니다. 정착·이음 길이에 반영됩니다. 공통 설정에서 확인하세요.`, target: 'common' });
   }
   const L = model.copingL * 1000;
   const B = model.copingB * 1000;
@@ -228,7 +228,7 @@ export function rebarSummary(
       }
     }
     for (const b of agg.values()) {
-      const split = splitPieces(b.length, 25.4, mFooting.fyS, mFooting.fck, STANDARD_BAR);
+      const split = splitPieces(b.length, 25.4, fyOf(mFooting, b.size), mFooting.fck, STANDARD_BAR);
       if (split && b.length > STANDARD_BAR && b.name !== 'B9') {
         rows.push({ member: 'footing', name: b.name, size: b.size, count: b.count, length: split.pieceLength, note: `${b.note}, 2조각 이음 (추천안, 겹침 ${Math.round(split.lap)})` });
         warnings.push({ code: 'RB-F08', message: `${b.name} 길이 ${Math.round(b.length)} mm > 정척 ${STANDARD_BAR} mm: 2조각 이음을 추천안으로 적용 (Q-B6).`, target: 'footing', bar: b.name });