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/index.ts

@@ -1,8 +1,39 @@
+export {
+    fetchAllFontshareFonts,
+    fetchFontshareFontBySlug,
+    fetchFontshareFonts,
+} from './api/fontshare';
+export type {
+    FontshareParams,
+    FontshareResponse,
+} from './api/fontshare';
+export {
+    fetchGoogleFontFamily,
+    fetchGoogleFonts,
+} from './api/googleFonts';
+export type {
+    GoogleFontItem,
+    GoogleFontsParams,
+    GoogleFontsResponse,
+} from './api/googleFonts';
+export {
+    normalizeFontshareFont,
+    normalizeFontshareFonts,
+    normalizeGoogleFont,
+    normalizeGoogleFonts,
+} from './api/normalize';
+export type {
+    FontFeatures,
+    FontMetadata,
+    FontStyleUrls,
+    UnifiedFont,
+    UnifiedFontVariant,
+} from './api/normalize';
 export type {
     FontCategory,
     FontProvider,
     FontSubset,
-} from './model/font';
+} from './model/types/font';
 export type {
     FontshareApiModel,
     FontshareDesigner,
@@ -13,10 +44,10 @@ export type {
     FontshareStyleProperties,
     FontshareTag,
     FontshareWeight,
-} from './model/fontshare_fonts';
+} from './model/types/fontshare_fonts';
 export type {
     FontFiles,
     FontItem,
     FontVariant,
     GoogleFontsApiModel,
-} from './model/google_fonts';
+} from './model/types/google_fonts';