fix(parse): reject split pier tables and block sheets that fail to build

- E05: a sheet whose pier, IP, or bearing table is not on the same sheet is
  not selectable (spec 2.2: one sheet per pier)
- a sheet is selectable only if every pier in it builds; the reason is shown
  next to the sheet instead of a selectable sheet with an unchecked pier

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

src/core/parseWorkbook.ts

@@ -78,9 +78,28 @@ function parseSheet(grid: Grid, sheet: string, issues: Issue[]): PierInput[] {
   }
 
   const piers: PierInput[] = [];
+  if (pierHeaders.length === 0 && (ipHeaders.length > 0 || bearingHeaders.length > 0)) {
+    issues.push({
+      code: 'E05',
+      level: 'E',
+      message: `${sheet}: 교각 정보 표가 이 시트에 없습니다. 교각 1기의 세 표(교각 정보·IP·받침)를 한 시트에 두세요 (시트 1장 = 교각 1기).`,
+    });
+  }
   for (const h of pierHeaders) {
     for (const { cells, index } of readBlock(grid, h)) {
       const name = String(cells[0]);
+      const pierIps = ips.filter((p) => p.pier === name);
+      const pierBearings = bearings.filter((b) => b.pier === name);
+      if (pierIps.length === 0 || pierBearings.length === 0) {
+        const missing = [pierIps.length === 0 ? 'IP' : null, pierBearings.length === 0 ? '받침' : null].filter(Boolean).join('·');
+        issues.push({
+          code: 'E05',
+          level: 'E',
+          pier: name,
+          message: `${index + 1}행: ${missing} 표가 이 시트에 없습니다. 교각 1기의 세 표를 한 시트에 두세요 (시트 1장 = 교각 1기).`,
+        });
+        continue;
+      }
       const bad = bearings.find((b) => b.pier === name && !b.azimuthOk);
       if (bad) {
         issues.push({