feat: 구글 프로필 이미지 업데이트 기능 추가

Author: lyouxsun

src/main/java/com/linku/backend/domain/user/User.java

@@ -81,4 +81,10 @@ public String getGoogleId() {
 
         return gMail.substring(0, atIndex);
     }
+
+    public void updatePictureIfEmpty(String picture) {
+        if (this.picture == null || this.picture.isBlank()) {
+            this.picture = picture;
+        }
+    }
 }

src/main/java/com/linku/backend/domain/user/service/UserService.java

@@ -27,7 +27,12 @@ public class UserService {
     @Transactional
     public User findOrCreateUser(GoogleUserInfo userInfo) {
         Optional<User> optionalUser = userRepository.findByProviderId(userInfo.sub());
-        return optionalUser.orElseGet(() -> userRepository.save(User.guest(userInfo)));
+        if (optionalUser.isPresent()) {
+            User existingUser = optionalUser.get();
+            existingUser.updatePictureIfEmpty(userInfo.picture());
+            return existingUser;
+        }
+        return userRepository.save(User.guest(userInfo));
     }
 
     public User getUserById(Long UserId) {