refactor(Font): consolidate API layer and update type structure

src/entities/Font/ui/FontApplicator/FontApplicator.svelte

@@ -16,19 +16,20 @@ import {
 
 interface Props {
     /**
-     * Applied font
+     * Font to apply
      */
     font: UnifiedFont;
     /**
      * Font weight
+     * @default 400
      */
     weight?: number;
     /**
-     * Additional classes
+     * CSS classes
      */
     className?: string;
     /**
-     * Children
+     * Content snippet
      */
     children?: Snippet;
 }
@@ -44,7 +45,7 @@ const status = $derived(
     appliedFontsManager.getFontStatus(
         font.id,
         weight,
-        font.features.isVariable,
+        font.features?.isVariable,
     ),
 );