feat(rebar): block rebar settings as input (S1·S2 spacing separate, S1 depth from the cover and bar diameters)

- PierInput.blockRebar (partial): cover top, side cover, first gap, spacing S1
  and S2 (separate), leg length. Defaults are the P1 values, so P1 is unchanged.
- S2 depth = top cover; S1 depth = top cover + S1/2 + S2/2 (H19: 69.1 at the default).
- The model carries the settings; the bearing-block rebar, the 3D bars, and the
  summary use them.

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

src/core/rebar/summary.ts

@@ -148,8 +148,8 @@ export function rebarSummary(
   if (shortest < anchorage) {
     warnings.push({ code: 'RB-S04', message: `받침블럭 철근 묻힘 ${Math.round(shortest)} mm < 정착길이 ${anchorage} mm (코핑 안 묻힘 부족)`, target: 'bearing' });
   }
-  rows.push({ member: 'bearing', name: 'S1', size: 'H19', count: blk.S1, length: barLength(), note: `블럭 배치 분리, 블럭당 8본 · 묻힘 ${range(emb1)} (블럭 상면 − 69.1)` });
-  rows.push({ member: 'bearing', name: 'S2', size: 'H19', count: blk.S2, length: barLength(), note: `블럭 배치 분리, 블럭당 8본 · 묻힘 ${range(emb2)} (블럭 상면 − 50)` });
+  rows.push({ member: 'bearing', name: 'S1', size: 'H19', count: blk.S1, length: barLength(1200, model.blockRebar), note: `블럭 배치 분리, 블럭당 8본 · 묻힘 ${range(emb1)} (블럭 상면 − 69.1)` });
+  rows.push({ member: 'bearing', name: 'S2', size: 'H19', count: blk.S2, length: barLength(1200, model.blockRebar), note: `블럭 배치 분리, 블럭당 8본 · 묻힘 ${range(emb2)} (블럭 상면 − 50)` });
 
   // Coping (코핑철근.md §5–§8)
   const width = widthLayout(B);