perf: 为 SiteSnapshotService.getActive 增加 Caffeine 本地缓存

- 缓存过期时间 10 分钟，最大 500 条
- publish 时主动刷新缓存，确保最新配置立即可用
- 避免 mediabot 每次请求都查数据库

par-core/src/main/java/com/par/core/service/impl/SiteSnapshotServiceImpl.java

@@ -2,6 +2,8 @@ package com.par.core.service.impl;
 
 import com.fasterxml.jackson.core.type.TypeReference;
 import com.fasterxml.jackson.databind.ObjectMapper;
+import com.github.benmanes.caffeine.cache.Cache;
+import com.github.benmanes.caffeine.cache.Caffeine;
 import com.par.common.util.HmacUtil;
 import com.par.core.adapter.GroovyScriptEngine;
 import com.par.core.entity.RiskRule;
@@ -19,6 +21,7 @@ import lombok.extern.slf4j.Slf4j;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 
+import java.time.Duration;
 import java.time.LocalDateTime;
 import java.util.LinkedHashMap;
 import java.util.List;
@@ -40,6 +43,12 @@ public class SiteSnapshotServiceImpl implements SiteSnapshotService {
     private final CachedStorageService storageService;
     private static final ObjectMapper om = new ObjectMapper();
 
+    /** 已发布快照本地缓存：key=siteId, value=SiteSnapshot */
+    private final Cache<String, SiteSnapshot> activeSnapshotCache = Caffeine.newBuilder()
+            .expireAfterWrite(Duration.ofMinutes(10))
+            .maximumSize(500)
+            .build();
+
     @Override
     public Map<String, Object> buildSnapshot(String siteId) {
         Map<String, Object> snapshot = new LinkedHashMap<>();
@@ -184,6 +193,9 @@ public class SiteSnapshotServiceImpl implements SiteSnapshotService {
         draft.setPublishedAt(LocalDateTime.now());
         snapshotMapper.updateById(draft);
 
+        // 刷新本地缓存
+        activeSnapshotCache.put(siteId, draft);
+
         // 上传到七牛云 CDN 作为灾备
         try {
             String bundleJson = toBundleJson(draft);
@@ -205,7 +217,10 @@ public class SiteSnapshotServiceImpl implements SiteSnapshotService {
 
     @Override
     public SiteSnapshot getActive(String siteId) {
+        return activeSnapshotCache.get(siteId, key -> {
+            log.debug("缓存未命中，查询数据库 siteId={}", siteId);
             return snapshotMapper.selectLatestPublished(siteId);
+        });
     }
 
     @Override