- Add Core API for multipart/form-data construction and encoding.
- Implement streaming support and flexible serialization strategies.
- Add support for explicit file inputs to prevent path ambiguity.
- Include Finch and Req adapters for seamless HTTP client integration.
- Implement robust validation for headers, parameters, and boundaries to
  prevent multipart injection attacks.
- Add comprehensive documentation, guides, and Apache 2.0 license.