Fix issue #18: Handle tokens without algorithm in protected headers

[kallal79]

This PR fixes issue #18 where tokens created by compile_token or other tools without algorithm information in protected headers could not be verified.

Problem

The original Evidence.Verify() function required the algorithm to be present in the COSE protected headers. When the algorithm was missing, verification would fail with an Error fetching alg message.

Solution

• Algorithm Inference: When protected.Algorithm() fails, the function now attempts to infer the algorithm from the public key type
• Supported Key Types: ECDSA keys (P-256 to ES256, P-384 to ES384, P-521 to ES512), EdDSA keys to EdDSA, RSA keys to PS256, Fallback to ES256 for unknown key types
• Backward Compatibility: Properly formed tokens with algorithm in protected headers continue to work as before

Changes

1. Modified Evidence.Verify() to handle missing algorithm gracefully
2. Added inferAlgorithmFromPublicKey() helper function with support for multiple key types
3. Exported InferAlgorithmFromPublicKey() for testing purposes
4. Added comprehensive tests covering the fix and algorithm inference functionality

Testing

• All existing tests continue to pass
• New tests verify algorithm inference for different key types
• Regression tests ensure normal verification still works

Fixes #18

[kallal79]

@thomas-fossati @yogeshbdeshpande @setrofim Fixes #18 by inferring alg from public key when missing in protected headers. All checks passed. Regression tests confirm compatibility.

Requesting review and assignment. Happy to clarify.