use seenEvents in IndexedDB

packages/system/src/index.ts

@@ -33,6 +33,7 @@ export * from "./query-optimizer";
 export * from "./encrypted";
 export * from "./outbox-model";
 export { parseIMeta } from "./utils";
+export * from "./seen-events";
 
 export * from "./impl/nip4";
 export * from "./impl/nip44";