feat: 토정비결 및 PDF 저장 기능 추가

- 토정비결 페이지 구현 (연간/월별 운세)
- 분야별 운세 (재물, 건강, 관운, 애정)
- PDF 저장 기능 구현 (jsPDF + html2canvas)
- 모든 결과 페이지에 PDF 다운로드 기능 추가
- PDFButton 재사용 가능한 컴포넌트 생성
- 홈페이지에 토정비결 링크 추가
- 페이지 간 네비게이션 링크 업데이트

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

app/compatibility/result/page.tsx

@@ -1,5 +1,6 @@
 import Link from 'next/link';
 import { calculateSaju, FIVE_ELEMENTS } from '@/lib/saju-calculator';
+import PDFButton from '../../components/PDFButton';
 
 interface PageProps {
   searchParams: Promise<{
@@ -178,7 +179,7 @@ export default async function CompatibilityResultPage({ searchParams }: PageProp
       </nav>
 
       {/* Result Content */}
-      <div className="max-w-6xl mx-auto px-4 py-12">
+      <div id="pdf-content" className="max-w-6xl mx-auto px-4 py-12">
         {/* Header */}
         <div className="text-center mb-12">
           <h1 className="text-4xl md:text-5xl font-bold text-gray-900 mb-4">
@@ -367,11 +368,12 @@ export default async function CompatibilityResultPage({ searchParams }: PageProp
             <p className="text-gray-600 text-sm">내 사주 확인하기</p>
           </Link>
 
-          <button className="bg-gradient-to-r from-pink-600 to-purple-600 text-white rounded-xl p-6 shadow-lg hover:shadow-xl transition text-center group">
-            <div className="text-4xl mb-3">📥</div>
-            <h3 className="text-xl font-bold mb-2">PDF 저장</h3>
-            <p className="text-sm opacity-90">궁합 결과 저장하기</p>
-          </button>
+          <PDFButton
+            elementId="pdf-content"
+            filename={`궁합_${year1}${month1}${day1}_${year2}${month2}${day2}.pdf`}
+            buttonText="궁합 PDF 저장"
+            className="bg-gradient-to-r from-pink-600 to-purple-600 text-white rounded-xl p-6 shadow-lg hover:shadow-xl transition text-center group w-full disabled:opacity-50 disabled:cursor-not-allowed"
+          />
         </div>
       </div>