break expense component into smaller pieces

src/app/services/category.service.ts

@@ -9,8 +9,6 @@ export class CategoryService {
   public readonly categories = this.internalCategories.asReadonly();
   public readonly categoryPath = 'http://localhost:3000/common-cents/categories';
 
-  // public categories = signal<Category[]>([]);
-
   public constructor(private readonly http: HttpService) {
     void this.fetchCategories();
   }