v0.2.1 - Add writeBinaryBatch method for batch file writes

What's New

Features

• New writeBinaryBatch method added to FileSystemService, OPFSBackend, and IndexedDBBackend
  • Supports progress tracking, concurrency control, and automatic parent directory creation
• Types and documentation added
• Added MIT LICENSE file
• Added npm keywords to package.json
• Fixed ESM import paths (added .js extensions)