feat: 콜드 스타트 문제 해결을 위한 Score Carry-Over 스케줄러 추가

- `carryOverRanking` 메서드를 `RankingService`에 추가하여 랭킹 데이터 이월 지원
- 이월 작업 자동화를 위한 `RankingScheduler` 구현 및 Cron 스케줄 설정
- Redis 연산을 활용한 이월 데이터 처리 및 만료 시간 설정 로직 추가

Author: yeonjiyeon

apps/commerce-api/src/main/java/com/loopers/application/rank/RankingScheduler.java

@@ -0,0 +1,35 @@
+package com.loopers.application.rank;
+
+import com.loopers.infrastructure.rank.RankingService;
+import java.time.LocalDateTime;
+import java.time.format.DateTimeFormatter;
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.scheduling.annotation.Scheduled;
+import org.springframework.stereotype.Component;
+
+@Slf4j
+@Component
+@RequiredArgsConstructor
+public class RankingScheduler {
+
+  private final RankingService rankingService;
+
+  @Scheduled(cron = "0 50 23 * * *")
+  public void scheduleRankingCarryOver() {
+    LocalDateTime now = LocalDateTime.now();
+    DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyyMMdd");
+
+    String today = now.format(formatter);
+    String tomorrow = now.plusDays(1).format(formatter);
+
+    log.info("Starting Ranking Carry-Over: {} -> {}", today, tomorrow);
+
+    try {
+      rankingService.carryOverRanking(today, tomorrow, 0.1);
+      log.info("Ranking Carry-Over completed successfully.");
+    } catch (Exception e) {
+      log.error("Ranking Carry-Over failed", e);
+    }
+  }
+}

apps/commerce-api/src/main/java/com/loopers/infrastructure/rank/RankingService.java

@@ -4,7 +4,10 @@
 import java.time.format.DateTimeFormatter;
 import java.util.List;
 import java.util.Set;
+import java.util.concurrent.TimeUnit;
 import lombok.RequiredArgsConstructor;
+import org.springframework.data.redis.connection.zset.Aggregate;
+import org.springframework.data.redis.connection.zset.Weights;
 import org.springframework.data.redis.core.RedisTemplate;
 import org.springframework.stereotype.Component;
 
@@ -38,4 +41,14 @@ public Integer getProductRank(Long productId) {
 
     return (rank != null) ? rank.intValue() + 1 : null;
   }
+
+  public void carryOverRanking(String sourceDate, String targetDate, double weight) {
+    String sourceKey = "ranking:all:" + sourceDate;
+    String targetKey = "ranking:all:" + targetDate;
+
+    redisTemplate.opsForZSet().unionAndStore(sourceKey, List.of(), targetKey,
+        Aggregate.SUM, Weights.of(weight));
+
+    redisTemplate.expire(targetKey, 2, TimeUnit.DAYS);
+  }
 }