refactor: clarify frontend module ownership

src/entities/brokerage-event/model/event-key.ts

@@ -0,0 +1,10 @@
+import type { BrokerageEvent } from "../api/useBrokerageEvents";
+
+function brokerageEventKey(event: BrokerageEvent) {
+	return JSON.stringify([
+		event.account?.id, event.type, event.date, event.instrumentUid,
+		event.figi, event.ticker, event.logoName,
+	]);
+}
+
+export { brokerageEventKey };