perf(cache): 三层缓存框架补强

- 新增 cache-framework skill，规范 RAM→Redis→DB 读路径、失效与 pub/sub
- 上传元数据 Otter+Redis 缓存与多节点失效；Auth Source 缓存与 pub/sub
- ListSystemConfigsByKeys 补 Redis 层；上传统计单事务；登录/Token 缓存预热
- cleanup 任务补 upload meta 失效钩子

internal/apps/upload/stats/stats_counter.go

@@ -37,7 +37,7 @@ func RebuildUploadStats(ctx context.Context) error {
 		}
 
 		for i := range uploads {
-			if err := applyUploadStatsDeltaTx(tx, &uploads[i], 1); err != nil {
+			if err := ApplyUploadStatsDeltaTx(tx, &uploads[i], 1); err != nil {
 				return err
 			}
 		}
@@ -50,11 +50,12 @@ func applyUploadStatsDelta(ctx context.Context, upload *model.Upload, sign int64
 		return nil
 	}
 	return db.DB(ctx).Transaction(func(tx *gorm.DB) error {
-		return applyUploadStatsDeltaTx(tx, upload, sign)
+		return ApplyUploadStatsDeltaTx(tx, upload, sign)
 	})
 }
 
-func applyUploadStatsDeltaTx(tx *gorm.DB, upload *model.Upload, sign int64) error {
+// ApplyUploadStatsDeltaTx applies incremental upload stats within an existing transaction.
+func ApplyUploadStatsDeltaTx(tx *gorm.DB, upload *model.Upload, sign int64) error {
 	if upload == nil || !isActiveUploadStatus(upload.Status) || sign == 0 {
 		return nil
 	}