feat(core): parse P1 workbook and build T-type pier shape

- parse Excel input by header strings (pier, IP, bearing tables)
- DMS azimuth parser (E03), input validation (E01, E02)
- pure geometry: axis, bearings, stepped coping, column, footing, piles, blinding
- warnings W01, W02, W05, W07, I01
- regression tests against spec.md section 12 (P1)

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

tests/validate-and-foundation.test.ts

@@ -0,0 +1,54 @@
+import { describe, expect, it } from 'vitest';
+import { buildPier } from '../src/core/geometry';
+import { validateInput, validatePier } from '../src/core/validate';
+import type { Issue, PierInput } from '../src/core/types';
+import { loadP1 } from './helpers';
+
+function run(input: PierInput): Issue[] {
+  const issues: Issue[] = [];
+  if (validateInput(input, issues)) validatePier(input, buildPier(input), issues);
+  return issues;
+}
+
+describe('validation (spec §10)', () => {
+  it('P1 raises I01 (block 100 mm < cover + bar 119 mm) and no E/W', () => {
+    const issues = run(loadP1());
+    expect(issues.map((i) => i.code)).toContain('I01');
+    expect(issues.filter((i) => i.level !== 'I')).toEqual([]);
+  });
+
+  it('E01 when the pier type and column count disagree', () => {
+    const issues = run({ ...loadP1(), type: '2주형' });
+    expect(issues.map((i) => i.code)).toContain('E01');
+  });
+
+  it('E02 when front and back bearing counts differ', () => {
+    const p1 = loadP1();
+    const issues: Issue[] = [];
+    const bad = { ...p1, bearings: p1.bearings.filter((b) => !(b.row === '후열' && b.no === 10)) };
+    expect(validateInput(bad, issues)).toBe(false);
+    expect(issues.map((i) => i.code)).toContain('E02');
+  });
+
+  it('W01 when IP2 disagrees with the 1:9 recalculation by more than 1 mm', () => {
+    const p1 = loadP1();
+    const ips = p1.ips.map((p) => (p.name === 'IP2' ? { ...p, x: p.x + 0.002 } : p));
+    expect(run({ ...p1, ips }).map((i) => i.code)).toContain('W01');
+  });
+});
+
+describe('foundation types', () => {
+  it('직접기초: footing, no piles', () => {
+    const m = buildPier({ ...loadP1(), foundationType: '직접기초' });
+    expect(m.footings).toHaveLength(1);
+    expect(m.piles).toHaveLength(0);
+  });
+
+  it('현장타설말뚝: no footing, one pile of column diameter per column, tip = bottom EL − length', () => {
+    const m = buildPier({ ...loadP1(), foundationType: '현장타설말뚝' });
+    expect(m.footings).toHaveLength(0);
+    expect(m.piles).toHaveLength(1);
+    expect(m.piles[0].diameter).toBeCloseTo(2.0, 6);
+    expect(m.piles[0].bottom).toBeCloseTo(26.208 - 24, 6);
+  });
+});