refactor(shared): rename fontCache to collectionCache

- Rename fontCache.ts to collectionCache.ts
- Rename FontCacheManager interface to CollectionCacheManager
- Make implementation fully generic (already was, just renamed interface)
- Update exports in shared/fetch/index.ts
- Fix getStats() to return derived store value for accurate statistics
- Add comprehensive test coverage for collection cache manager
  - 41 test cases covering all functionality
  - Tests for caching, deduplication, state tracking
  - Tests for statistics, reactivity, and edge cases

Closes task-1 of Phase 1 refactoring

src/entities/Font/api/index.ts

@@ -0,0 +1,39 @@
+/**
+ * Font API clients exports
+ *
+ * Exports API clients and normalization utilities
+ */
+
+export {
+    fetchGoogleFontFamily,
+    fetchGoogleFonts,
+} from './googleFonts';
+export type {
+    GoogleFontItem,
+    GoogleFontsParams,
+    GoogleFontsResponse,
+} from './googleFonts';
+
+export {
+    fetchAllFontshareFonts,
+    fetchFontshareFontBySlug,
+    fetchFontshareFonts,
+} from './fontshare';
+export type {
+    FontshareParams,
+    FontshareResponse,
+} from './fontshare';
+
+export {
+    normalizeFontshareFont,
+    normalizeFontshareFonts,
+    normalizeGoogleFont,
+    normalizeGoogleFonts,
+} from './normalize';
+export type {
+    FontFeatures,
+    FontMetadata,
+    FontStyleUrls,
+    UnifiedFont,
+    UnifiedFontVariant,
+} from './normalize';