feat(rebar): B10-2 최하단 단 삭제, 측면 B2 다리선 강조 (모서리 연결)

- B10-2 최하단(z = c_b)도 하면 1단 B2·B4와 같은 높이에서 간섭하므로 삭제 (승인 2026-10-26)
- B10-2: 18 → 16본 (8단 × 2면). 표와 3D가 같은 규칙
- 단면 그림의 측면 B2 다리선을 굵은 주황 실선으로 그려 모서리 연결을 드러냄
- 테스트 기대값 갱신 (B10-2 16)

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

src/view/footing-section-svg.ts

@@ -102,7 +102,8 @@ export function footingSectionSvg(model: PierModel): string {
     const xSide = i === 0 ? xSideL : xSideR;
     parts.push(line('ext', 'B1', xx, xSide, y(z.B1), COLOR.b14, 1));
     parts.push(line('ext', 'B2', xx, xSide, y(z.B24), COLOR.b14, 1));
-    parts.push(vline('leg', 'B2', xSide, y(z.B1), y(z.B24), COLOR.b14));
+    // The B2 side leg (up to the B1 height at the side cover) is drawn heavier, so the corner reads as one run (승인 2026-10-26).
+    parts.push(`<line class="leg" data-bar="B2" x1="${xSide.toFixed(1)}" x2="${xSide.toFixed(1)}" y1="${y(z.B1).toFixed(1)}" y2="${y(z.B24).toFixed(1)}" stroke="${COLOR.b14}" stroke-width="1.8"/>`);
   }
 
   // B9: one purple vertical line per row along W (the rows of b9Bars).

src/view/rebar3d.ts

@@ -462,7 +462,8 @@ export function buildRebar3D(m: PierModel, common: Material = DEFAULT_MATERIAL,
       for (const sg of [-1, 1]) {
         // B10-2: across W at the L faces; its ends turn inward along s.
         const sp = f.s + sg * sEdge;
-        polyline('B10-2', [[sp - sg * hookB10, zj, -nEdge], [sp, zj, -nEdge], [sp, zj, nEdge], [sp - sg * hookB10, zj, nEdge]], NOMINAL_DIAMETER.S19);
+        // The lowest B10-2 level is removed (승인 2026-10-26): the 하면 1단 B2·B4 take its place at the corner.
+        if (j > 0) polyline('B10-2', [[sp - sg * hookB10, zj, -nEdge], [sp, zj, -nEdge], [sp, zj, nEdge], [sp - sg * hookB10, zj, nEdge]], NOMINAL_DIAMETER.S19);
         // B10-1: along s at the W faces, 19.1 above B10-2; its ends turn inward along n.
         const np = sg * nEdge;
         const zb = zj + dB10;