Update key pair sanity check mechanism

The key pair sanity check mechanism in the hsm.go file has been updated. Previously, it used the `CKM_SHA256` mechanism from the pkcs11 package, but now it is using the `CKM_ECDSA_SHA256` mechanism. This change helps to improve the security of the key pair verification process.

service/internal/security/hsm.go

@@ -498,7 +498,7 @@ func (h *HSMSession) LoadECKey(info KeyInfo) (*ECKeyPair, error) {
 	pair.PublicKey = ecPublicKey
 
 	// Do a sanity check of the key pair
-	mechanism := []*pkcs11.Mechanism{pkcs11.NewMechanism(pkcs11.CKM_SHA256, nil)}
+	mechanism := []*pkcs11.Mechanism{pkcs11.NewMechanism(pkcs11.CKM_ECDSA_SHA256, nil)}
 	err = h.ctx.SignInit(h.sh, mechanism, keyHandleEC)
 	if err != nil {
 		slog.Error("pkcs11 SignInit", "err", err)