add reversibility on category level

src/infrastructure/Repository/IRepository.ts

@@ -3,6 +3,7 @@ import { IEntity } from '../Entity/IEntity';
 export interface IRepository<TKey, TEntity extends IEntity<TKey>> {
     readonly length: number;
     getItems(predicate?: (entity: TEntity) => boolean): TEntity[];
+    getById(id: TKey): TEntity | undefined;
     addItem(item: TEntity): void;
     addOrUpdateItem(item: TEntity): void;
     removeItem(id: TKey): void;