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/core/rebar/summary.ts

@@ -164,12 +164,16 @@ export function linkedSpacing(name: string, model: PierModel): Pick<RebarRow, 's
   // B10 s_v; B11·B12 4s. The basis is 기본값 unless the grid spacing s or s_v differs from its default.
   const fs = model.footingRebar;
   const fd = DEFAULT_FOOTING_REBAR;
-  if (/^B[1-8]$/.test(name)) {
-    const cycle = name === 'B2' || name === 'B4' || name === 'B6' || name === 'B8';
-    return { spacing: String(2 * fs.s), actual: String(cycle ? fs.s : 2 * fs.s), basis: basis(fs.s !== fd.s) };
+  if (/^B[1-4]$/.test(name)) {
+    const cycle = name === 'B2' || name === 'B4';
+    return { spacing: String(2 * fs.sAxis), actual: String(cycle ? fs.sAxis : 2 * fs.sAxis), basis: basis(fs.sAxis !== fd.sAxis) };
   }
-  if (name === 'B9') return { spacing: `${4 * fs.s} (4s)`, actual: `${2 * fs.s} (2s 엇갈림)`, basis: basis(fs.s !== fd.s) };
-  if (name === 'B11' || name === 'B12') return { spacing: `${4 * fs.s} (4s)`, actual: String(4 * fs.s), basis: basis(fs.s !== fd.s) };
+  if (/^B[5-8]$/.test(name)) {
+    const cycle = name === 'B6' || name === 'B8';
+    return { spacing: String(2 * fs.sPerp), actual: String(cycle ? fs.sPerp : 2 * fs.sPerp), basis: basis(fs.sPerp !== fd.sPerp) };
+  }
+  if (name === 'B9') return { spacing: `${4 * fs.sAxis} (4s)`, actual: `${2 * fs.sAxis} (2s 엇갈림)`, basis: basis(fs.sAxis !== fd.sAxis) };
+  if (name === 'B11' || name === 'B12') return { spacing: `${4 * fs.sPerp} (4s)`, actual: String(4 * fs.sPerp), basis: basis(fs.sPerp !== fd.sPerp) };
   if (name === 'B10-1' || name === 'B10-2') return { spacing: String(fs.sV), actual: String(fs.sV), basis: basis(fs.sV !== fd.sV) };
   if (name === 'S1') return { spacing: String(b.spacingS1), actual: String(b.spacingS1), basis: basis(b.spacingS1 !== bd.spacingS1) };
   if (name === 'S2') return { spacing: String(b.spacingS2), actual: String(b.spacingS2), basis: basis(b.spacingS2 !== bd.spacingS2) };