feat(utils): add generic buildQueryString utility

- Add type-safe buildQueryString function to /utils
- Support primitives, arrays, and optional values
- Proper URL encoding for special characters
- Add comprehensive tests (25 test cases, all passing)
- Update Google Fonts API client to use shared utility
- Update Fontshare API client to use shared utility
- Export utility from /utils/index.ts

Benefits:
- DRY - Single source of truth for query string logic
- Type-safe - Proper TypeScript support with QueryParams type
- Tested - Comprehensive test coverage
- Maintainable - One place to fix bugs

src/entities/Font/api/index.ts

@@ -7,33 +7,33 @@
 export {
     fetchGoogleFontFamily,
     fetchGoogleFonts,
-} from './googleFonts';
+} from './google/googleFonts';
 export type {
     GoogleFontItem,
     GoogleFontsParams,
     GoogleFontsResponse,
-} from './googleFonts';
+} from './google/googleFonts';
 
 export {
     fetchAllFontshareFonts,
     fetchFontshareFontBySlug,
     fetchFontshareFonts,
-} from './fontshare';
+} from './fontshare/fontshare';
 export type {
     FontshareParams,
     FontshareResponse,
-} from './fontshare';
+} from './fontshare/fontshare';
 
 export {
     normalizeFontshareFont,
     normalizeFontshareFonts,
     normalizeGoogleFont,
     normalizeGoogleFonts,
-} from './normalize';
+} from './normalize/normalize';
 export type {
     FontFeatures,
     FontMetadata,
     FontStyleUrls,
     UnifiedFont,
     UnifiedFontVariant,
-} from './normalize';
+} from './normalize/normalize';