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.test.ts

@@ -53,6 +53,16 @@ vi.mock('$shared/lib/helpers/createPersistentStore/createPersistentStore.svelte'
 
 vi.mock('$entities/Font', async importOriginal => {
     const actual = await importOriginal<typeof import('$entities/Font')>();
+    return {
+        ...actual,
+        getFontUrl: vi.fn(() => 'https://example.com/font.woff2'),
+    };
+});
+
+// Stores moved behind the model segment; mock them there. FontsByIdsStore is
+// intentionally left real (spread from actual) so $state reactivity works.
+vi.mock('$entities/Font/model', async importOriginal => {
+    const actual = await importOriginal<typeof import('$entities/Font/model')>();
     return {
         ...actual,
         fontCatalogStore: { fonts: [] },
@@ -63,7 +73,6 @@ vi.mock('$entities/Font', async importOriginal => {
             getFontStatus: vi.fn(),
             ready: vi.fn(() => Promise.resolve()),
         },
-        getFontUrl: vi.fn(() => 'https://example.com/font.woff2'),
     };
 });
 
@@ -84,11 +93,11 @@ vi.mock('$features/AdjustTypography/model', () => ({
     },
 }));
 
+import * as proxyFonts from '$entities/Font/api/proxy/proxyFonts';
 import {
     fontCatalogStore,
     fontLifecycleManager,
-} from '$entities/Font';
-import * as proxyFonts from '$entities/Font/api/proxy/proxyFonts';
+} from '$entities/Font/model';
 import { ComparisonStore } from './comparisonStore.svelte';
 
 describe('ComparisonStore', () => {