Reapply "feat(rebar): B1–B4와 B5–B8 방향 교환 (B1–B4는 W 방향, B5–B8은 L 방향)"

사용자 요청으로 방향 교환을 다시 적용 (99db6a1 되돌림). 격자 키 sL/sW, 3D·단면·철근표 역할과 테스트 기대값이 교환 기준으로 돌아감.

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

tests/footing-rebar-inputs.test.ts

@@ -9,17 +9,17 @@ const footingRows = (input: Parameters<typeof buildPier>[0]) =>
 const count = (rows: ReturnType<typeof footingRows>, name: string) => rows.find((r) => r.name === name)!.count;
 
 describe('확대기초 철근은 입력 치수를 따른다 (3단계, 승인 2026-10-23)', () => {
-  it('P1 footing rebar is unchanged with the default inputs (B1 31, B5 40, B9 306)', () => {
+  it('P1 footing rebar is unchanged with the default inputs (B1 40, B5 31, B9 306; 방향 교환 후)', () => {
     const rows = footingRows(loadP1());
-    expect(count(rows, 'B1')).toBe(31);
-    expect(count(rows, 'B5')).toBe(40);
+    expect(count(rows, 'B1')).toBe(40);
+    expect(count(rows, 'B5')).toBe(31);
     expect(count(rows, 'B9')).toBe(306);
   });
 
   it('a wider footing (W 9000) and a longer one (L 11000) add bars to B1–B4 and B5–B8', () => {
     const rows = footingRows({ ...loadP1(), footingWidthMm: 9000, footingLengthMm: 11000 });
-    expect(count(rows, 'B1')).toBeGreaterThan(31);
-    expect(count(rows, 'B5')).toBeGreaterThan(40);
+    expect(count(rows, 'B1')).toBeGreaterThan(40);
+    expect(count(rows, 'B5')).toBeGreaterThan(31);
   });
 
   it('a different footing height (2200) is computed without error, and the 3D rebar still builds', () => {