chore(deps): upgrade oxyjwt to >=0.7.0 and drop pyjwt / cryptography

[ZhuchkaTriplesix]

Summary

• Upgraded oxyjwt dev/bench dependency to >=0.7.0 which supports asymmetric keys and algorithms (RSA, PSS, ECDSA, EdDSA) natively via Rust aws_lc_rs.
• Replaced PyJWT token signing in tests/test_jwt_rs256.py with oxyjwt.EncodingKey.from_rsa_pem.
• Removed pyjwt and cryptography from pyproject.toml dev and bench dependencies.
• Updated docs/jwt.md and perf-test/bench_scenarios.sh.