Function validate_token_with_jwk 

pub fn validate_token_with_jwk<T: DeserializeOwned>(
    token: &str,
    jwk: &Jwk,
    alg: Algorithm,
) -> Result<T, String>

Validates a JWT token using a specific JWK key.

This function performs the actual cryptographic validation of the JWT using the provided JWK and algorithm. It returns the decoded claims if validation succeeds.