fix: [payslip] PDF 급여명세서 font-weight 800 → bold 수정

- DomPDF에 NanumGothic bold(700)까지만 등록되어 weight 800 한글이 깨짐
- h1, .net-row의 font-weight: 800 → bold로 변경

resources/views/emails/payslip.blade.php

@@ -5,7 +5,7 @@
     <style>
         body { font-family: 'NanumGothic', 'Malgun Gothic', sans-serif; margin: 0; padding: 20px; background: #fff; }
         .container { max-width: 720px; margin: 0 auto; background: #fff; padding: 40px 36px; }
-        h1 { text-align: center; font-size: 22px; font-weight: 800; letter-spacing: 2px; margin: 0 0 28px; border-bottom: 3px solid #333; padding-bottom: 16px; }
+        h1 { text-align: center; font-size: 22px; font-weight: bold; letter-spacing: 2px; margin: 0 0 28px; border-bottom: 3px solid #333; padding-bottom: 16px; }
         .info-table { width: 100%; border-collapse: collapse; margin-bottom: 20px; table-layout: fixed; }
         .info-table td { padding: 6px 8px; font-size: 12px; border: 1px solid #999; overflow: hidden; }
         .info-table .label { font-weight: bold; background: #f0f0f0; text-align: center; }
@@ -15,7 +15,7 @@
         .payslip-table .item-name { text-align: center; }
         .payslip-table .item-amount { text-align: right; }
         .payslip-table .total-row td { font-weight: 700; background: #f8f8f8; }
-        .payslip-table .net-row td { font-weight: 800; font-size: 14px; background: #f0f7ff; }
+        .payslip-table .net-row td { font-weight: bold; font-size: 14px; background: #f0f7ff; }
         .footer-table { width: 100%; margin-top: 20px; padding-top: 12px; border: none; }
         .footer-table td { font-size: 12px; color: #666; border: none; padding: 0; }
     </style>