refactor: findUserDetails이 UserResponse 사용하도록 수정

Author: huncozyboy

src/main/java/leets/weeth/domain/user/application/usecase/UserUseCase.java

@@ -23,7 +23,7 @@ public interface UserUseCase {
 
     List<AdminResponse> findAllByAdmin();
 
-    Response findUserDetails(Long userId);
+    UserResponse findUserDetails(Long userId);
 
     void update(Update dto, Long userId);