feat: add underline animation

- Implement underline-animation UnoCSS shortcut for navbar links
- Add dynamic hover and page transition effects for navigation
- Update Navbar component to use new underline-animation class
- Remove CDN configuration from preload settings
- Modify font class for date display in index page
- Add inline script to handle link animations during page transitions

src/types/index.d.ts

@@ -77,7 +77,6 @@ export interface ThemeConfig {
   }
 
   preload: {
-    cdn: string
     commentURL?: string
     imageHostURL?: string
     customGoogleAnalyticsURL?: string