refactor: MemerService 및 JoinService Trasactional 정리

src/main/java/com/sanbosillok/sanbosillokserver/api/member/service/JoinService.java

@@ -10,14 +10,17 @@
 import lombok.RequiredArgsConstructor;
 import org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder;
 import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
 
 @Service
 @RequiredArgsConstructor
+@Transactional(readOnly = true)
 public class JoinService {
     private final MemberRepository memberRepository;
     private final ImageService imageService;
     private final BCryptPasswordEncoder bCryptPasswordEncoder;
 
+    @Transactional
     public void join(JoinRequest joinRequest) {
         if (!memberRepository.existsByUsername(joinRequest.getUsername())) {
 

src/main/java/com/sanbosillok/sanbosillokserver/api/member/service/MemberService.java

@@ -24,6 +24,7 @@ public List<MemberResponse> getInactiveMembers() {
                 .collect(Collectors.toList());
     }
 
+    @Transactional
     public void activateMember(Long id) {
         Member member = memberRepository.findById(id)
                 .orElseThrow(() -> new IllegalArgumentException("해당 회원 가입 신청이 존재하지 않습니다."));