feat(core,view): bent coping stage 2 — mitred coping, stretch-local bearings, blocks and columns

- buildPier builds on buildAxis: each object carries its stretch k and a local
  s from that stretch's base; coping parts are per stretch with the mitre plane
  trimming the overlap in the scene (renderer.localClippingEnabled).
- Straight P1 output is unchanged (regression tests pass).
- Bent coping is supported for 현장타설말뚝 only; footings and piles on a bent
  axis remain 미실시 until stage 3. Kink outside the coping and columns within
  the Level half-width of the kink are refused.
- W03/W04 use coping coordinates (g).
- Tests: constructed 60° bend — world coordinates of bearings, blocks and the
  column survive the stretch frames; mitre sides; scene mesh count; refusals.

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

src/core/validate.ts

@@ -6,7 +6,7 @@ const EXPECTED_COLUMNS: Record<PierType, number> = { 'T형': 1, '2주형': 2, '3
 /** Rules from spec §10 that are not implemented in this stage. Shown to the user, never silently skipped. */
 export const NOT_IMPLEMENTED_RULES = [
   'E04 fck 미입력 (배근 단계, 3단계)',
-  '꺾인 코핑 형상 (IP4 꺾임각 ≠ 0; IP4 계산식만 구현)',
+  '꺾인 코핑의 확대기초·말뚝 (3단계; 현장타설말뚝만 지원)',
   'W06 속성 복사 건너뜀 (2단계)',
   'W08 솔플레이트 T1−T2 검사 (2단계)',
 ] as const;
@@ -51,7 +51,7 @@ export function validatePier(input: PierInput, model: PierModel, issues: Issue[]
   const halfBlock = DIM.blockSize / 2;
   const stepBounds = model.segments.slice(1).map((seg) => seg.s0);
   for (const b of model.bearings) {
-    const nearest = Math.min(...stepBounds.map((s) => Math.abs(b.s - s)));
+    const nearest = Math.min(...stepBounds.map((s) => Math.abs(b.g - s)));
     if (nearest < halfBlock) {
       issues.push({
         code: 'W03',
@@ -65,8 +65,8 @@ export function validatePier(input: PierInput, model: PierModel, issues: Issue[]
   const planHalfB = model.copingB / 2;
   const outside = model.blocks.some(
     (b) =>
-      b.s - halfBlock < 0 ||
-      b.s + halfBlock > model.copingL ||
+      b.g - halfBlock < 0 ||
+      b.g + halfBlock > model.copingL ||
       b.n - halfBlock < -planHalfB ||
       b.n + halfBlock > planHalfB,
   );