refactor: replace export* barrels with explicit named exports

Wildcard re-exports obscure each slice public surface and weaken
tree-shaking. Convert to explicit named re-exports with export/export
type split (B-1) for ComparisonView, ChangeAppTheme, Breadcrumb/model,
and FilterAndSortFonts/api barrels.

src/features/Breadcrumb/model/index.ts

@@ -1,2 +1,7 @@
-export * from './store/scrollBreadcrumbsStore.svelte';
-export * from './types/types.ts';
+export {
+    __resetScrollBreadcrumbsStore,
+    createScrollBreadcrumbsStore,
+    getScrollBreadcrumbsStore,
+} from './store/scrollBreadcrumbsStore.svelte';
+export type { BreadcrumbItem } from './store/scrollBreadcrumbsStore.svelte';
+export type { NavigationAction } from './types/types.ts';

src/features/ChangeAppTheme/index.ts

@@ -1,2 +1,2 @@
-export * from './model';
-export * from './ui';
+export { getThemeManager } from './model';
+export { ThemeSwitch } from './ui';

src/features/FilterAndSortFonts/api/index.ts

@@ -1 +1,6 @@
-export * from './filters/filters';
+export { fetchProxyFilters } from './filters/filters';
+export type {
+    FilterMetadata,
+    FilterOption,
+    ProxyFiltersResponse,
+} from './filters/filters';