fix(bearing): C4·C5 are the 교축 distances from the bearing to the block edges (승인 2026-10-26)

- bearingEdgeDistances now reads the block geometry: 분리 1200 blocks are
  centred on the bearing (600 / 600); 일체 uses the pair's 2500 block (outer
  margins 601, within the 5 mm tolerance of 600).
- The plan labels C4 and C5 from these values; the coping-edge definition is removed.

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

tests/bearing-plan-svg.test.ts

@@ -7,10 +7,10 @@ const separate = buildPier(loadP1());
 const integrated = buildPier({ ...loadP1(), bearingLayout: '일체' });
 
 describe('교량받침 상세 평면 (승인 2026-10-26)', () => {
-  it('shows C4 and C5 across the coping width (P1 front 852 / 2248)', () => {
+  it('shows C4 and C5 from the bearing to the block edges along the 교축 (600 each)', () => {
     const svg = bearingPlanSvg(separate, 0);
-    expect(svg).toContain('C4 852');
-    expect(svg).toContain('C5 950');
+    expect(svg).toContain('C4 600');
+    expect(svg).toContain('C5 600');
   });
 
   it('분리 draws two 1200 outlines; 일체 draws one 2500 outline (block outline only)', () => {