refactor: clean up SEO and theme configuration

- Remove unused SEO metadata fields like Facebook and site screenshot
- Rename global font configuration from 'font' to 'fontStyle'
- Update theme toggle to use documentElement instead of body for theme restoration
- Simplify HTML metadata and remove redundant meta tags
- Adjust index page to use div instead of time for date display

src/styles/global.css

@@ -80,7 +80,7 @@ html:not(.dark) {
 }
 
 @supports not (view-transition-name: none) {
-  body:not([data-restore-theme]) {
+  html:not([data-restore-theme]) {
     --at-apply: 'transition-colors duration-500 ease-in-out';
   }
 }