fix: add @reference directive for Tailwind 4 scoped styles

Add @reference 'tailwindcss' to components using @apply in scoped styles:
- MainNavigation.vue
- SubNavigation.vue
- GlobalSearchBar.vue

Required for Tailwind CSS 4 compatibility with scoped Vue styles.

app/components/search/GlobalSearchBar.vue

@@ -209,6 +209,8 @@ onMounted(() => {
 </script>
 
 <style scoped>
+@reference "tailwindcss";
+
 .search-field {
   @apply flex flex-col px-4 py-2 min-w-32;
 }