equals method
Checks if this private key is equal to another
Implementation
@override
Future<bool> equals(p2pkeys.PrivateKey other) async {
if (other is! RsaPrivateKey) return false;
// Compare public keys (modulus and exponent)
final publicKeyEquals = await _publicKey.equals(other.publicKey);
if (!publicKeyEquals) return false;
// Compare private exponent
return _key.privateExponent == other._key.privateExponent;
}