feat(view): shear-segment table for 2·3주형 on the ③ coping tab

The segment table lists each column's Level and the segments between columns
(추천안, Q-K2), so a 2주형 shows 좌 경사 3, Level 1 9, Level 2 9, 기둥 사이 1 18,
우 경사 3. One column is unchanged.

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

tests/rebar-coping-lengths.test.ts

@@ -47,3 +47,16 @@ describe('전단철근 구간 표 (시안 ③)', () => {
     expect([right.from, right.to, right.count, right.spacing]).toEqual([7450, 11700, 18, 250]);
   });
 });
+
+describe('전단철근 구간 표 다주형', () => {
+  it('2주형 (columns 2400 and 9600): left 3, Level 1 9, Level 2 9, between 18, right 3', () => {
+    const segs = shearSegments(12000, [2400, 9600]);
+    expect(segs.map((g) => [g.segment, g.count])).toEqual([
+      ['좌 경사', 3],
+      ['Level 1', 9],
+      ['Level 2', 9],
+      ['기둥 사이 1', 18],
+      ['우 경사', 3],
+    ]);
+  });
+});