add: common에 dto/successRespnse 추가

common/src/main/java/com/ktds/hi/common/dto/SuccessResponse.java

@@ -0,0 +1,56 @@
+package com.ktds.hi.common.dto;
+
+import com.fasterxml.jackson.annotation.JsonInclude;
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+
+import java.time.LocalDateTime;
+
+/**
+ * 성공 응답 DTO 클래스
+ * 간단한 성공 메시지를 반환할 때 사용
+ */
+@Getter
+@Builder
+@NoArgsConstructor
+@AllArgsConstructor
+@JsonInclude(JsonInclude.Include.NON_NULL)
+public class SuccessResponse {
+
+    private boolean success;
+    private String message;
+    private LocalDateTime timestamp;
+
+    /**
+     * 성공 응답 생성 (메시지 포함)
+     */
+    public static SuccessResponse of(String message) {
+        return SuccessResponse.builder()
+                .success(true)
+                .message(message)
+                .timestamp(LocalDateTime.now())
+                .build();
+    }
+
+    /**
+     * 성공 응답 생성 (기본 메시지)
+     */
+    public static SuccessResponse success() {
+        return SuccessResponse.builder()
+                .success(true)
+                .message("성공")
+                .timestamp(LocalDateTime.now())
+                .build();
+    }
+
+    /**
+     * 생성자 (메시지만)
+     */
+    public SuccessResponse(String message) {
+        this.success = true;
+        this.message = message;
+        this.timestamp = LocalDateTime.now();
+    }
+}