[add] Recently, memory activities have adopted Redis caching.

api/app/cache/memory/__init__.py

@@ -4,7 +4,9 @@ Memory 缓存模块
 提供记忆系统相关的缓存功能
 """
 from .interest_memory import InterestMemoryCache
+from .activity_stats_cache import ActivityStatsCache
 
 __all__ = [
     "InterestMemoryCache",
+    "ActivityStatsCache",
 ]