feat: Set Pretendard as default font

src/styles/index.css

@@ -1,5 +1,6 @@
+@import url('https://cdnjs.cloudflare.com/ajax/libs/pretendard/1.3.9/static/pretendard.min.css');
 @import 'tailwindcss';
-@import "tw-animate-css";
+@import 'tw-animate-css';
 
 @custom-variant dark (&:is(.dark *));
 
@@ -113,6 +114,10 @@
 @layer base {
   * {
     @apply border-border outline-ring/50;
+    font-family: 'Pretendard Variable', Pretendard, -apple-system,
+      BlinkMacSystemFont, system-ui, Roboto, 'Helvetica Neue', 'Segoe UI',
+      'Apple SD Gothic Neo', 'Noto Sans KR', 'Malgun Gothic',
+      'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol', sans-serif;
   }
   body {
     @apply bg-background text-foreground;