feat(rebar): dimensions on the block rebar plan

- The S2 layout along the 교축 (below the block), the S1 layout along the 교각축
  (beside it), and the block width, in the same form as the C–C section.

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

tests/block-rebar-plan-svg.test.ts

@@ -26,3 +26,17 @@ describe('받침블럭 배근 평면 (승인 2026-10-26)', () => {
     expect(svg).toContain('>S1<');
   });
 });
+
+describe('받침블럭 배근 평면 치수 (승인 2026-10-26)', () => {
+  it('shows the S2 layout 162.5 · 7@125=875 · 162.5 and the block width 1200', () => {
+    const svg = blockRebarPlanSvg(buildPier(loadP1()), 0);
+    expect(svg).toContain('162.5 · 7@125=875 · 162.5');
+    expect(svg).toContain('>1200<');
+  });
+
+  it('a 일체 pair shows the 2500 block width and the 19-bar S2 layout', () => {
+    const svg = blockRebarPlanSvg(buildPier({ ...loadP1(), bearingLayout: '일체' }), 0);
+    expect(svg).toContain('>2500<');
+    expect(svg).toContain('@125=2250');
+  });
+});