JSON Web Key/Signature/Encryption Toolkit

## Description:
Create a comprehensive toolkit for working with JWK, JWS, and JWE standards.

## User Story:
As a web developer, I need to work with JWT tokens and JWK key sets for authentication and authorization.

Features:
- Parse and validate JWK key sets
- Sign and verify JWS tokens
- Encrypt and decrypt JWE tokens
- Key conversion to/from JWK format

## Acceptance Criteria:
- [ ] Support all JWK key types
- [ ] JWS signing/verification works
- [ ] JWE encryption/decryption works
- [ ] Key format conversion