WinnerController Swagger 문서화 추가 및 이벤트/참여자 예외 처리 개선

- WinnerController에 Swagger 어노테이션 추가 (Operation, Parameter, ParameterObject)
- 당첨자 목록 조회 API 기본 정렬 설정 (winnerRank ASC, size=20)
- ParticipationService에서 이벤트/참여자 구분 로직 개선
  - 이벤트 없음: EventNotFoundException 발생
  - 참여자 없음: ParticipantNotFoundException 발생
- EventCacheService 제거 (Redis 기반 검증에서 DB 기반 검증으로 변경)

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

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

participation-service/src/main/resources/application.yml

@@ -18,7 +18,7 @@ spring:
   # JPA 설정
   jpa:
     hibernate:
-      ddl-auto: ${DDL_AUTO:update}
+      ddl-auto: ${DDL_AUTO:validate}
     show-sql: ${SHOW_SQL:true}
     properties:
       hibernate:
@@ -26,9 +26,23 @@ spring:
         dialect: org.hibernate.dialect.PostgreSQLDialect
         default_batch_fetch_size: 100
 
+  # Redis 설정
+  data:
+    redis:
+      host: ${REDIS_HOST:20.214.210.71}
+      port: ${REDIS_PORT:6379}
+      password: ${REDIS_PASSWORD:Hi5Jessica!}
+      timeout: 3000ms
+      lettuce:
+        pool:
+          max-active: 8
+          max-idle: 8
+          min-idle: 2
+          max-wait: -1ms
+
   # Kafka 설정
   kafka:
-    bootstrap-servers: ${KAFKA_BOOTSTRAP_SERVERS:4.230.50.63:9092}
+    bootstrap-servers: ${KAFKA_BOOTSTRAP_SERVERS:4.217.131.59:9095}
     producer:
       key-serializer: org.apache.kafka.common.serialization.StringSerializer
       value-serializer: org.springframework.kafka.support.serializer.JsonSerializer
@@ -50,6 +64,8 @@ logging:
     com.kt.event.participation: ${LOG_LEVEL:INFO}
     org.hibernate.SQL: DEBUG
     org.hibernate.type.descriptor.sql.BasicBinder: TRACE
+    org.springframework.kafka: DEBUG
+    org.apache.kafka: DEBUG
   file:
     name: ${LOG_FILE:logs/participation-service.log}
   logback: