feat(fonts): implement Phase 2 - Unified Font Store

- Implemented UnifiedFontStore extending BaseFontStore
- Added pagination support with derived metadata
- Added provider-specific shortcuts (setProvider, setCategory, etc.)
- Added pagination methods (nextPage, prevPage, goToPage)
- Added category getter shortcuts (sansSerifFonts, serifFonts, etc.)
- Updated store exports to include unified store
- Fixed typo in googleFontsStore.svelte.ts (createGoogleFontsStore)

Phase 2/7: Proxy API Integration for GlyphDiff

src/entities/Font/model/store/googleFontsStore.svelte.ts

@@ -20,7 +20,7 @@ export class GoogleFontsStore extends BaseFontStore<GoogleFontsParams> {
     }
 }
 
-export function createFontshareStore(params: GoogleFontsParams = {}) {
+export function createGoogleFontsStore(params: GoogleFontsParams = {}) {
     return new GoogleFontsStore(params);
 }