refactor(font): expose stores via model segment, not the top barrel

Re-exporting the store singletons (fontCatalogStore, fontLifecycleManager,
FontsByIdsStore) through entities/Font/index.ts meant every consumer of the
barrel eager-instantiated stores and pulled @tanstack/query-core — in dev,
test, and as retained code. Drop the store re-export from the top barrel;
keep the pure surface (types, constants, domain, lib, ui) there for
convenience. Consumers that need stores import $entities/Font/model.
Aligns with the BaseQueryStore carve-out: barrel by default, segment path
when it would drag a heavy or side-effectful dependency.

src/widgets/ComparisonView/model/stores/comparisonStore.svelte.ts

@@ -15,12 +15,14 @@
 
 import {
     type FontLoadRequestConfig,
-    FontsByIdsStore,
     type UnifiedFont,
-    fontCatalogStore,
-    fontLifecycleManager,
     getFontUrl,
 } from '$entities/Font';
+import {
+    FontsByIdsStore,
+    fontCatalogStore,
+    fontLifecycleManager,
+} from '$entities/Font/model';
 import { typographySettingsStore } from '$features/AdjustTypography/model';
 import { createPersistentStore } from '$shared/lib';
 import { untrack } from 'svelte';