participation-service: CORS 설정 추가

- ParticipationController, DebugController, WinnerController에 @CrossOrigin 애노테이션 추가
- http://localhost:3000에서의 크로스 오리진 요청 허용
- 프론트엔드 개발 환경과의 연동을 위한 CORS 해결

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

participation-service/src/main/java/com/kt/event/participation/presentation/controller/DebugController.java

@@ -12,6 +12,7 @@ import java.util.List;
  * 디버깅용 컨트롤러
  */
 @Slf4j
+@CrossOrigin(origins = "http://localhost:3000")
 @RestController
 @RequestMapping("/debug")
 @RequiredArgsConstructor

participation-service/src/main/java/com/kt/event/participation/presentation/controller/ParticipationController.java

@@ -25,6 +25,7 @@ import org.springframework.web.bind.annotation.*;
  * @since 2025-01-24
  */
 @Slf4j
+@CrossOrigin(origins = "http://localhost:3000")
 @RestController
 @RequestMapping("/api/v1")
 @RequiredArgsConstructor

participation-service/src/main/java/com/kt/event/participation/presentation/controller/WinnerController.java

@@ -8,11 +8,10 @@ import com.kt.event.participation.application.dto.ParticipationResponse;
 import com.kt.event.participation.application.service.WinnerDrawService;
 import io.swagger.v3.oas.annotations.Operation;
 import io.swagger.v3.oas.annotations.Parameter;
-import io.swagger.v3.oas.annotations.tags.Tag;
-import org.springdoc.core.annotations.ParameterObject;
 import jakarta.validation.Valid;
 import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
+import org.springdoc.core.annotations.ParameterObject;
 import org.springframework.data.domain.Pageable;
 import org.springframework.data.domain.Sort;
 import org.springframework.data.web.PageableDefault;
@@ -26,6 +25,7 @@ import org.springframework.web.bind.annotation.*;
  * @since 2025-01-24
  */
 @Slf4j
+@CrossOrigin(origins = "http://localhost:3000")
 @RestController
 @RequestMapping("/api/v1")
 @RequiredArgsConstructor