Strengthen validation retries and checkpoint safety

internal/modules/dnd/validate/npcregistry/identity/validator_test.go

@@ -57,6 +57,9 @@ func TestValidatorDefersShapeAndRejectsIdentityIssues(t *testing.T) {
 	if err != nil || result.Approved || result.ReasonCode != ReasonCode {
 		t.Fatalf("identity result = %#v, error = %v, want rejection", result, err)
 	}
+	if err := contracts.ValidateValidationResult(result); err != nil {
+		t.Fatalf("ValidateValidationResult() error = %v for %#v", err, result)
+	}
 	for _, want := range []string{"invalid_id", "duplicate_canonical_identity", "duplicate_id", "npcs[0]", "npcs[1]"} {
 		if !strings.Contains(result.Message, want) {
 			t.Fatalf("identity message %q missing %q", result.Message, want)