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

crates/aether-data/src/repository/users/memory.rs

@@ -95,6 +95,29 @@ impl UserReadRepository for InMemoryUserReadRepository {
             .collect())
     }
 
+    async fn list_users_by_username_search(
+        &self,
+        username_search: &str,
+    ) -> Result<Vec<StoredUserSummary>, DataLayerError> {
+        let username_search = username_search.trim().to_ascii_lowercase();
+        if username_search.is_empty() {
+            return Ok(Vec::new());
+        }
+
+        Ok(self
+            .by_id
+            .read()
+            .expect("user repository lock")
+            .values()
+            .filter(|user| {
+                user.username
+                    .to_ascii_lowercase()
+                    .contains(&username_search)
+            })
+            .cloned()
+            .collect())
+    }
+
     async fn list_non_admin_export_users(
         &self,
     ) -> Result<Vec<StoredUserExportRow>, DataLayerError> {

crates/aether-data/src/repository/users/sql.rs

@@ -21,6 +21,20 @@ WHERE id = ANY($1::text[])
 ORDER BY id ASC
 "#;
 
+const LIST_USERS_BY_USERNAME_SEARCH_SQL: &str = r#"
+SELECT
+  id,
+  username,
+  email,
+  role::text AS role,
+  is_active,
+  is_deleted
+FROM users
+WHERE is_deleted IS FALSE
+  AND LOWER(username) LIKE $1
+ORDER BY id ASC
+"#;
+
 const LIST_NON_ADMIN_EXPORT_USERS_SQL: &str = r#"
 SELECT
   id,
@@ -199,6 +213,24 @@ impl SqlxUserReadRepository {
         .await
     }
 
+    pub async fn list_users_by_username_search(
+        &self,
+        username_search: &str,
+    ) -> Result<Vec<StoredUserSummary>, DataLayerError> {
+        let username_search = username_search.trim();
+        if username_search.is_empty() {
+            return Ok(Vec::new());
+        }
+
+        collect_query_rows(
+            sqlx::query(LIST_USERS_BY_USERNAME_SEARCH_SQL)
+                .bind(format!("%{}%", username_search.to_ascii_lowercase()))
+                .fetch(&self.pool),
+            map_user_row,
+        )
+        .await
+    }
+
     pub async fn list_non_admin_export_users(
         &self,
     ) -> Result<Vec<StoredUserExportRow>, DataLayerError> {
@@ -383,6 +415,13 @@ impl UserReadRepository for SqlxUserReadRepository {
         self.list_users_by_ids(user_ids).await
     }
 
+    async fn list_users_by_username_search(
+        &self,
+        username_search: &str,
+    ) -> Result<Vec<StoredUserSummary>, DataLayerError> {
+        self.list_users_by_username_search(username_search).await
+    }
+
     async fn list_non_admin_export_users(
         &self,
     ) -> Result<Vec<StoredUserExportRow>, DataLayerError> {

crates/aether-data/src/repository/users/types.rs

@@ -393,6 +393,11 @@ pub trait UserReadRepository: Send + Sync {
         user_ids: &[String],
     ) -> Result<Vec<StoredUserSummary>, crate::DataLayerError>;
 
+    async fn list_users_by_username_search(
+        &self,
+        username_search: &str,
+    ) -> Result<Vec<StoredUserSummary>, crate::DataLayerError>;
+
     async fn list_export_users(&self) -> Result<Vec<StoredUserExportRow>, crate::DataLayerError>;
 
     async fn list_export_users_page(