feat(parse): report per-sheet recognition and block error sheets

- parseWorkbook returns a report per sheet (table counts, issues, ok)
- sheets with E-level issues cannot be selected (spec section 2.3)
- pier input carries its source sheet name

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

src/core/geometry.ts

@@ -118,6 +118,7 @@ export interface PierModel {
     columnHeight: number;
     soilCover: number;
     pileCount: number;
+    pileLayout: string | null;
     pileTipEl: number | null;
     blockHeightFront: number;
     blockHeightBack: number;
@@ -290,6 +291,7 @@ export function buildPier(input: PierInput): PierModel {
       columnHeight: levelBottom - columns[0].bottom,
       soilCover: input.groundEl - (input.foundationType === '현장타설말뚝' ? input.footingBottomEl : footingTop),
       pileCount: piles.length,
+      pileLayout: input.foundationType === '말뚝기초' ? pileLayoutText() : null,
       pileTipEl: piles.length ? pileTip : null,
       blockHeightFront,
       blockHeightBack,
@@ -313,12 +315,26 @@ function segmentTop(segments: Segment[], s: number): number {
  * Piles under one footing (spec §4.6): rows across the footing width, piles along the length,
  * both with an end distance of 0.7 m and an even spacing that never exceeds 2.25 m.
  */
-export function pilesFor(s: number, topEl: number, length: number): PileModel[] {
+export function pileGrid(): { countS: number; countN: number; spacingS: number; spacingN: number } {
   const span = (size: number) => Math.floor((size - 2 * DIM.pileEnd) / DIM.pileSpacing) + 1;
   const countS = span(DIM.footingL);
   const countN = span(DIM.footingW);
-  const spacingS = (DIM.footingL - 2 * DIM.pileEnd) / (countS - 1);
-  const spacingN = (DIM.footingW - 2 * DIM.pileEnd) / (countN - 1);
+  return {
+    countS,
+    countN,
+    spacingS: (DIM.footingL - 2 * DIM.pileEnd) / (countS - 1),
+    spacingN: (DIM.footingW - 2 * DIM.pileEnd) / (countN - 1),
+  };
+}
+
+/** Display string such as "4@2250 × 3@2250 = 20본" (gaps along the length × gaps across the width). */
+export function pileLayoutText(): string {
+  const g = pileGrid();
+  return `${g.countS - 1}@${Math.round(g.spacingS * 1000)} × ${g.countN - 1}@${Math.round(g.spacingN * 1000)} = ${g.countS * g.countN}본`;
+}
+
+export function pilesFor(s: number, topEl: number, length: number): PileModel[] {
+  const { countS, countN, spacingS, spacingN } = pileGrid();
   const out: PileModel[] = [];
   for (let i = 0; i < countS; i++) {
     for (let j = 0; j < countN; j++) {