fix(rebar): column heights Hc and h_cop from the model (Level underside, step top) instead of P1 constants

Hc = Level underside − footing top, and h_cop = step top at the column centre − Level underside. P1 gives 12703 and 2644,
unchanged. With taper h2 = 3000 the Level underside moves down, so Hc = 11203 and the P2 top (Level underside + l_d)
moves to 13039, while the P1 top stays at the step top (15147). The 3D and the 철근표 use the same heights.

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

src/core/rebar/summary.ts

@@ -3,7 +3,7 @@ import { barLength, bearingBlockRebar, totals } from './bearing-block';
 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 { sideRowLevels } from '../coping-geom';
-import { columnRebar, COLUMN_P1 } from './column';
+import { columnRebar, columnInputFor } from './column';
 import { bottomBars, crossBars, sideBars, assemblyBars, shearB9 } from './footing';
 import { DEFAULT_MATERIAL, FckByMember, fyOf, isAssumedMaterial, Material, materialFor, splitPieces } from './common';
 
@@ -209,7 +209,7 @@ export function rebarSummary(
   rows.push({ member: 'coping', name: 'C16', size: 'H19', count: stairs.c16.length, length: stairs.c16[0].length, note: `계단부, 3·4구간 (${Math.round(stairs.c16[0].length)} / ${Math.round(stairs.c16[stairs.c16.length - 1].length)})` });
 
   // Column (기둥철근.md · plan C4), P1 defaults
-  const col = columnRebar(COLUMN_P1, mColumn);
+  const col = columnRebar(columnInputFor(model), mColumn);
   rows.push({ member: 'column', name: 'P1', size: 'S32', count: col.mainP1, length: null, pieces: col.p1Pieces.map((length) => ({ length, count: col.mainP1 })), note: `외측 r ${col.r1}, 마디 ${col.p1Pieces.join(' / ')} (첫 마디에 갈고리 ${col.p1Hook}, 기둥철근.md §3.2)` });
   rows.push({ member: 'column', name: 'P2', size: 'S32', count: col.mainP2, length: null, pieces: col.p2Pieces.map((length) => ({ length, count: col.mainP2 })), note: `내측 r ${col.r2}, 마디 ${col.p2Pieces.join(' / ')}` });
   rows.push({ member: 'column', name: '주철근 커플러', size: 'D32용 (L150 Ø60)', count: col.couplers, length: 150, note: '@3000, P2는 +150 mm 상향 엇갈림' });