feat(input): use RAG/운곡교P1입력.xlsx as the P1 input

- public/samples/운곡교P1입력.xlsx is a byte copy of RAG/운곡교P1입력.xlsx
- loadP1 and the sample loader read the three-sheet input
- spec workbook (intent.PR) stays for the single-sheet regression tests
- test: input file has sheets 교각 · IP · 받침 and parses to P1 with no issues

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

tests/parse.test.ts

@@ -1,7 +1,7 @@
 import * as XLSX from 'xlsx';
 import { describe, expect, it } from 'vitest';
 import { parseWorkbook } from '../src/core/parseWorkbook';
-import { loadP1, loadWorkbook } from './helpers';
+import { loadInputWorkbook, loadP1, loadWorkbook } from './helpers';
 
 describe('parseWorkbook (P1 sheet intent.PR)', () => {
   it('finds exactly one pier P1 with the input values of the sheet', () => {
@@ -92,3 +92,13 @@ describe('three-sheet input (교각 · IP · 받침 on separate sheets, joined b
     ]);
   });
 });
+
+describe('user input file (RAG/운곡교P1입력.xlsx)', () => {
+  it('has the three sheets 교각 · IP · 받침 and parses to one pier, P1, with no issues', () => {
+    const wb = loadInputWorkbook();
+    expect(wb.SheetNames).toEqual(['교각', 'IP', '받침']);
+    const { piers, issues } = parseWorkbook(wb);
+    expect(issues).toEqual([]);
+    expect(piers.map((p) => [p.name, p.sheet])).toEqual([['P1', '교각']]);
+  });
+});