refactor(Font/model): move baseFontStore and unifiedFontStore to subdirectories, rename errors/index to errors/errors

src/entities/Font/model/store/index.ts

@@ -11,7 +11,7 @@ export {
     createUnifiedFontStore,
     type UnifiedFontStore,
     unifiedFontStore,
-} from './unifiedFontStore.svelte';
+} from './unifiedFontStore/unifiedFontStore.svelte';
 
 // Applied fonts manager (CSS loading - unchanged)
 export { appliedFontsManager } from './appliedFontsStore/appliedFontsStore.svelte';