perf(usage): user-me usage 查询避免全量加载，默认限制 7 天范围

- UsageAuditListQuery 新增 limit 字段，支持在 SQL 层 LIMIT
- user-me usage 端点无时间范围时默认查最近 7 天
- active usage 端点无 ids 过滤时限制查最近 1 小时
- InMemory 实现同步支持 limit truncate

apps/aether-gateway/src/handlers/admin/observability/stats/range.rs

@@ -26,6 +26,7 @@ pub(crate) async fn list_usage_for_range(
             provider_name: filters.provider_name.clone(),
             model: filters.model.clone(),
             statuses: None,
+            limit: None,
         })
         .await
 }
@@ -46,6 +47,7 @@ pub(crate) async fn list_usage_for_optional_range(
                     provider_name: filters.provider_name.clone(),
                     model: filters.model.clone(),
                     statuses: None,
+                    limit: None,
                 })
                 .await
         }

apps/aether-gateway/src/handlers/admin/observability/usage/analytics/cache_affinity.rs

@@ -17,6 +17,7 @@ pub(in super::super) async fn list_recent_completed_usage_for_cache_affinity(
             provider_name: None,
             model: None,
             statuses: None,
+            limit: None,
         })
         .await?;
     items.retain(|item| item.status == "completed");