feat(rebar): block rebar settings card and C–C section on the ③ bearing tab

- Six inputs with their ranges and P1 defaults; a change regenerates the pier.
- The 적용 블럭 line shows the blocks (분리 n개 or 일체 n쌍, 전체).
- view/block-rebar-svg.ts: the section C–C along the 교축 with the S2 dots, the
  S1 lines and legs, and the dimensions (block widths, the S2 layout).
- 받침블럭 철근 설정 is tracked for changes (defaults vs the current draft).

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

src/core/changes.ts

@@ -23,7 +23,7 @@ export const EDITABLE_FIELDS = [
 ] as const;
 
 /** Inputs tracked for overrides and pending changes: the numeric cards plus 열별 본수 (an array, compared by value). */
-export const TRACKED_KEYS = [...EDITABLE_FIELDS.map((f) => f.key), 'pileRows', 'groundPosition', 'groundWaterOn', 'groundWaterEl', 'floodLevelEl', 'scourDepthM', 'highWaterEl', 'lowWaterEl', 'strataRows', 'bearingType', 'bearingLayout'] as const;
+export const TRACKED_KEYS = [...EDITABLE_FIELDS.map((f) => f.key), 'pileRows', 'groundPosition', 'groundWaterOn', 'groundWaterEl', 'floodLevelEl', 'scourDepthM', 'highWaterEl', 'lowWaterEl', 'strataRows', 'bearingType', 'bearingLayout', 'blockRebar'] as const;
 
 export type EditableKey = (typeof TRACKED_KEYS)[number];
 
@@ -53,6 +53,7 @@ export const FIELD_LABELS: Record<EditableKey, string> = {
   lowWaterEl: '저조위 LWL',
   bearingType: '받침 종류·용량',
   bearingLayout: '받침 배치',
+  blockRebar: '받침블럭 철근 설정',
   strataRows: '지층 행',
 };