feat(offsite): 异地副本加入 registry 用户镜像，按摘要加密去重，索引按版本保留 14 天，新增 fetch-images 回推恢复

internal/watchdog/probes.go

@@ -361,8 +361,8 @@ func OffsiteFinding(statusFile string, now time.Time) *Finding {
 	}
 	f := &Finding{
 		Key: "offsite", Severity: Warning, For: backupFor,
-		Summary:   "异地备份从未成功同步过，世界归档与数据库备份只在本机",
-		SummaryEN: "the off-site copy has never completed; world archives and database bundles exist on this machine only",
+		Summary:   "异地备份从未成功同步过，世界归档、数据库备份与用户镜像只在本机",
+		SummaryEN: "the off-site copy has never completed; world archives, database bundles and user images exist on this machine only",
 		Hint:      hint,
 	}
 	if st != nil && !st.LastSuccess.IsZero() {