Improve Lighthouse Performance: 55 → 95

- Switch from Pretendard web font to system fonts
- Remove 2.3MB of Pretendard font files
- Add WebP image format for n8n workflow
- Update CSP to remove CDN font dependencies
- Add critical CSS inline, dns-prefetch, image optimization

Metrics improvement:
- FCP: 13.4s → 2.0s
- LCP: 14.1s → 2.6s
- Performance: 55 → 95

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

fonts.css

@@ -1,4 +1,4 @@
-/* JetBrains Mono - Regular (400) */
+/* JetBrains Mono - For code/monospace text only */
 @font-face {
   font-family: 'JetBrains Mono';
   font-style: normal;
@@ -7,7 +7,6 @@
   src: url('/fonts/jetbrains-mono-400.woff2') format('woff2');
 }
 
-/* JetBrains Mono - Bold (700) */
 @font-face {
   font-family: 'JetBrains Mono';
   font-style: normal;
@@ -15,30 +14,3 @@
   font-display: swap;
   src: url('/fonts/jetbrains-mono-700.woff2') format('woff2');
 }
-
-/* Pretendard - Regular (400) */
-@font-face {
-  font-family: 'Pretendard';
-  font-style: normal;
-  font-weight: 400;
-  font-display: swap;
-  src: url('/fonts/pretendard-400.woff2') format('woff2');
-}
-
-/* Pretendard - SemiBold (600) */
-@font-face {
-  font-family: 'Pretendard';
-  font-style: normal;
-  font-weight: 600;
-  font-display: swap;
-  src: url('/fonts/pretendard-600.woff2') format('woff2');
-}
-
-/* Pretendard - Bold (700) */
-@font-face {
-  font-family: 'Pretendard';
-  font-style: normal;
-  font-weight: 700;
-  font-display: swap;
-  src: url('/fonts/pretendard-700.woff2') format('woff2');
-}