RefreshTokenDestroyed 콜백 명칭 수정, LicenseCheckInterval 최솟값 버그 수정 및 불필요 using 정리

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

BaronSoftware.SSO/Exceptions/InvalidUserException.cs

@@ -1,10 +1,4 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
-
-namespace BaronSoftware.SSO
+namespace BaronSoftware.SSO
 {
     public class InvalidUserException : Exception
     {

BaronSoftware.SSO/Exceptions/UserJsonParsingException.cs

@@ -1,10 +1,4 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
-
-namespace BaronSoftware.SSO
+namespace BaronSoftware.SSO
 {
     public class UserJsonParsingException : Exception
     {