feat: 회원정보 변경시 이메일 중복 검사

backend/src/main/java/com/edufocus/edufocus/user/controller/UserController.java

@@ -65,7 +65,7 @@ public class UserController {
             userService.changePassword(passwordDto, userId);
             return ResponseEntity.ok("Password changed successfully");
         } catch (Exception e) {
-            return ResponseEntity.badRequest().body(e.getMessage());
+            return ResponseEntity.status(HttpStatus.NOT_ACCEPTABLE).body(e.getMessage());
         }
     }
 

backend/src/main/java/com/edufocus/edufocus/user/model/service/UserServiceImpl.java

@@ -74,6 +74,12 @@ public class UserServiceImpl implements UserService {
 
         User user = userRepository.findById(id).orElseThrow(IllegalArgumentException::new);
 
+
+        if (isEmailExist(infoDto.getEmail())) {
+            throw new IllegalArgumentException("이미 사용 중인 이메일입니다.");
+
+        }
+
         if (infoDto.getName() != null)
             user.setName(infoDto.getName());