refactor: change projection and anchor navigation

apps/angular/1-projection/src/app/data-access/city.store.ts

@@ -0,0 +1,23 @@
+import { Injectable } from '@angular/core';
+import { BehaviorSubject } from 'rxjs';
+import { City } from '../model/city.model';
+
+@Injectable({
+  providedIn: 'root',
+})
+export class CityStore {
+  private cities = new BehaviorSubject<City[]>([]);
+  cities$ = this.cities.asObservable();
+
+  addAll(cities: City[]) {
+    this.cities.next(cities);
+  }
+
+  addOne(student: City) {
+    this.cities.next([...this.cities.value, student]);
+  }
+
+  deleteOne(id: number) {
+    this.cities.next(this.cities.value.filter((s) => s.id !== id));
+  }
+}