feat(gateway/data): 新增 usage 关键词搜索、缓存命中摘要、结算成本摘要及 dashboard 聚合查询能力

- 新增 UsageAuditKeywordSearchQuery，支持多关键词、用户名、API Key 交叉过滤
- 新增 UsageCacheHitSummaryQuery/StoredUsageCacheHitSummary，统计请求缓存命中率
- 新增 UsageSettledCostSummaryQuery/StoredUsageSettledCostSummary，汇总结算成本
- 新增 UsageDashboardSummaryQuery、UsageBreakdownSummaryQuery 等 dashboard 聚合类型
- SQL 层实现对应查询方法，含 list_by_ids、list_usage_audits_by_keyword_search、count_usage_audits_by_keyword_search
- 将上述能力通过 GatewayDataState / AdminAppState 暴露给 handler 层
- user_me_usage 及 dashboard_filters 切换为新查询接口，移除旧的内存过滤逻辑
- 同步更新 memory 层及测试

apps/aether-gateway/src/tests/architecture/admin_shared.rs

@@ -161,8 +161,6 @@ fn admin_wrapped_state_owns_observability_capabilities() {
         "pub(crate) fn has_auth_api_key_data_reader(&self) -> bool",
         "pub(crate) fn has_user_data_reader(&self) -> bool",
         "pub(crate) async fn list_provider_catalog_providers(",
-        "pub(crate) async fn list_admin_usage_for_range(",
-        "pub(crate) async fn list_admin_usage_for_optional_range(",
         "pub(crate) async fn aggregate_finalized_request_candidate_timeline_by_endpoint_ids_since(",
         "pub(crate) async fn read_recent_request_candidates(",
         "pub(crate) fn provider_key_rpm_reset_at(",
@@ -175,6 +173,15 @@ fn admin_wrapped_state_owns_observability_capabilities() {
             "handlers/admin/request/mod.rs should expose observability capability {pattern}"
         );
     }
+    for pattern in [
+        "pub(crate) async fn list_admin_usage_for_range(",
+        "pub(crate) async fn list_admin_usage_for_optional_range(",
+    ] {
+        assert!(
+            !admin_request.contains(pattern),
+            "handlers/admin/request/mod.rs should not expose deprecated unbounded usage helper {pattern}"
+        );
+    }
 }
 
 #[test]