✨ feat: implement core Cereale library for JSON mapping and validation

- 🎨 add Spring-like decorators (@JsonSerialize, @JsonDeserialize, etc.)
- ⚙️ implement JsonMapper and metadata storage for transformations
- 🧪 add comprehensive test suite using Vitest
- 📝 add README, CONTRIBUTING, and API documentation
- 👷 setup GitHub Actions CI workflow
- 🔧 configure TypeScript and project settings

.gitignore

@@ -22,3 +22,6 @@ yarn-error.log*
 
 # Coverage
 /coverage/
+
+# ESLint
+.eslintcache