Refactor: ApiRespinse 수정 (#130)

## #️⃣연관된 이슈

> #50

## 📝작업 내용

> ResponseEntity -> ApiRespnse

### 스크린샷 
<img width="1150" height="264" alt="image"
src="https://github.com/user-attachments/assets/66acddb7-27cf-4a97-942e-ec1717f07296"
/>

Author: 2anizirong

src/main/java/EatPic/spring/domain/user/controller/UserController.java

@@ -4,10 +4,7 @@
 import EatPic.spring.domain.user.dto.*;
 import EatPic.spring.domain.user.dto.request.LoginRequestDTO;
 import EatPic.spring.domain.user.dto.request.SignupRequestDTO;
-import EatPic.spring.domain.user.dto.response.CheckEmailResponseDTO;
-import EatPic.spring.domain.user.dto.response.CheckNicknameResponseDTO;
-import EatPic.spring.domain.user.dto.response.LoginResponseDTO;
-import EatPic.spring.domain.user.dto.response.SignupResponseDTO;
+import EatPic.spring.domain.user.dto.response.*;
 import EatPic.spring.domain.user.service.UserService;
 import EatPic.spring.global.common.ApiResponse;
 import EatPic.spring.global.common.code.status.ErrorStatus;
@@ -70,9 +67,17 @@ public ApiResponse<CheckEmailResponseDTO> checkEmail(@RequestParam String email)
     // 유저 아이디 중복 검사
     @GetMapping("/check-user-id")
     @Operation(summary = "유저 아이디 중복 검사")
-    public ApiResponse<Map<String, Boolean>> checkUserId(@RequestParam String nameId) {
+    public ApiResponse<CheckNameIdResponseDTO> checkUserId(@RequestParam String nameId) {
         boolean isDuplicate = userService.isnameIdDuplicate(nameId);
-        return ApiResponse.onSuccess(Map.of("isDuplicate", isDuplicate));
+
+        if(isDuplicate) {
+            return ApiResponse.onFailure(
+                    ErrorStatus.DUPLICATE_NAMEID.getCode(),
+                    ErrorStatus.DUPLICATE_NAMEID.getMessage(),
+                    UserConverter.toCheckNameIdResponseDTO(nameId, false)
+            );
+        }
+        return ApiResponse.onSuccess(UserConverter.toCheckNameIdResponseDTO(nameId, true));
     }
 
     // 닉네임 중복 검사

src/main/java/EatPic/spring/domain/user/converter/UserConverter.java

@@ -4,10 +4,7 @@
 import EatPic.spring.domain.reaction.dto.ReactionResponseDTO;
 import EatPic.spring.domain.reaction.entity.ReactionType;
 import EatPic.spring.domain.user.dto.UserInfoDTO;
-import EatPic.spring.domain.user.dto.response.CheckEmailResponseDTO;
-import EatPic.spring.domain.user.dto.response.CheckNicknameResponseDTO;
-import EatPic.spring.domain.user.dto.response.LoginResponseDTO;
-import EatPic.spring.domain.user.dto.response.UserResponseDTO;
+import EatPic.spring.domain.user.dto.response.*;
 import EatPic.spring.domain.user.entity.User;
 import EatPic.spring.domain.user.mapping.UserBlock;
 import EatPic.spring.domain.user.mapping.UserFollow;
@@ -99,14 +96,22 @@ public static UserResponseDTO.UserActionResponseDto toUserActionResponseDto(User
                 .build();
     }
 
-    // 유저 아이디 중복 검사
+    // 이메일 중복 검사
     public static CheckEmailResponseDTO toCheckEmailResponseDTO(String email, boolean isDuplicate){
         return CheckEmailResponseDTO.builder()
                 .email(email)
                 .isDuplicate(isDuplicate)
                 .build();
     }
 
+    // 이메일 중복 검사
+    public static CheckNameIdResponseDTO toCheckNameIdResponseDTO(String nameId, boolean isDuplicate){
+        return new CheckNameIdResponseDTO().builder()
+                .nameId(nameId)
+                .isDuplicate(isDuplicate)
+                .build();
+    }
+
     // 닉네임 중복 검사
     public static CheckNicknameResponseDTO toCheckNicknameResponseDto(String nickname, boolean isDuplicate) {
         return CheckNicknameResponseDTO.builder()

src/main/java/EatPic/spring/domain/user/dto/response/CheckNameIdResponseDTO.java

@@ -0,0 +1,15 @@
+package EatPic.spring.domain.user.dto.response;
+
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+
+@Builder
+@Getter
+@NoArgsConstructor
+@AllArgsConstructor
+public class CheckNameIdResponseDTO {
+    private String nameId;
+    private boolean isDuplicate;
+}