feat(rebar): 격자 실간격을 교각축(B1–B4·B9)과 교각축 직각(B5–B8·B11·B12)으로 나눠 입력

- footing-settings: s → sAxis(교각축) · sPerp(교각축 직각), 범위는 동일 (100–150)
- grid·gridPositions가 방향 키를 받음. B1–B4 grid는 sAxis, B5–B8 grid는 sPerp, B9 행·열은 sAxis, B11·B12는 sPerp
- 철근표 간격·실간격과 근거가 방향별 값을 씀 (B12는 교각축 직각 값, 승인 2026-10-26)
- 3D 확대기초 그림의 위치도 방향별 값을 씀
- 패널 입력 두 칸으로 분리

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

src/view/rebar3d.ts

@@ -385,9 +385,9 @@ export function buildRebar3D(m: PierModel, common: Material = DEFAULT_MATERIAL,
     const fs = m.footingRebar;
     const z = layers(Hf, fs);
     const gW = grid(Wf * 1000, fs);
-    const gL = grid(Lf * 1000, fs);
-    const posW = (j: number) => -Wf / 2 + mm(fs.cSide + gW.e + j * fs.s);
-    const posL = (i: number) => -Lf / 2 + mm(fs.cSide + gL.e + i * fs.s);
+    const gL = grid(Lf * 1000, fs, 'sPerp');
+    const posW = (j: number) => -Wf / 2 + mm(fs.cSide + gW.e + j * fs.sAxis);
+    const posL = (i: number) => -Lf / 2 + mm(fs.cSide + gL.e + i * fs.sPerp);
     const sA = -Lf / 2 + 0.1;
     const sB = Lf / 2 - 0.1;
     const nA = -Wf / 2 + 0.1;
@@ -470,8 +470,8 @@ export function buildRebar3D(m: PierModel, common: Material = DEFAULT_MATERIAL,
       }
     }
     // B11 (across W, spread along L) and B12 (along L, spread across W) at the assembly levels, 4s apart, 2s stagger per level.
-    const xsL = gridPositions(Lf * 1000, fs);
-    const ysW = gridPositions(Wf * 1000, fs);
+    const xsL = gridPositions(Lf * 1000, fs, 'sPerp');
+    const ysW = gridPositions(Wf * 1000, fs, 'sPerp');
     const dAsm = assemblyEndOffset();
     const nAsm = Wf / 2 - mm(d1 + dAsm);
     const sAsm = Lf / 2 - mm(d2 + dAsm);