feat(gateway): unify background task runtime and storage

crates/aether-data/src/repository/background_tasks/mod.rs

@@ -0,0 +1,17 @@
+mod memory;
+mod mysql;
+mod postgres;
+mod sqlite;
+
+#[allow(unused_imports)]
+pub(crate) use aether_data_contracts::repository::background_tasks::{
+    BackgroundTaskKind, BackgroundTaskListQuery, BackgroundTaskReadRepository,
+    BackgroundTaskRepository, BackgroundTaskStatus, BackgroundTaskSummary,
+    BackgroundTaskWriteRepository, StoredBackgroundTaskEvent, StoredBackgroundTaskRun,
+    StoredBackgroundTaskRunPage, UpsertBackgroundTaskEvent, UpsertBackgroundTaskRun,
+};
+
+pub use memory::InMemoryBackgroundTaskRepository;
+pub use mysql::MysqlBackgroundTaskRepository;
+pub use postgres::SqlxBackgroundTaskRepository;
+pub use sqlite::SqliteBackgroundTaskRepository;