perf: improve LCP — move font loading to HTML, defer logo preload

- Move Google Fonts from CSS @import (render-blocking) to <link> in
  index.html with preconnect for earlier discovery
- Remove @import from globals.css — browser no longer waits for CSS
  parse -> @import fetch -> font CSS parse before first paint
- Defer initLogoPreload() to requestIdleCallback so logo fetch
  doesn't compete with critical resources during page load

src/styles/globals.css

@@ -1,5 +1,3 @@
-@import url('https://fonts.googleapis.com/css2?family=Manrope:wght@400;500;600;700;800&display=swap');
-
 @tailwind base;
 @tailwind components;
 @tailwind utilities;