feat: implement cart icon component with quantity badge and integrate into store header for improved UI

src/app/shared/components/cart-icon/cart-icon.component.ts

@@ -0,0 +1,19 @@
+import { ChangeDetectionStrategy, Component, computed, input } from '@angular/core';
+
+@Component({
+  selector: 'app-cart-icon',
+  imports: [],
+  templateUrl: './cart-icon.component.html',
+  styleUrl: './cart-icon.component.scss',
+  changeDetection: ChangeDetectionStrategy.OnPush
+})
+export class CartIconComponent {
+  readonly quantity = input<number | null | undefined>(undefined);
+  readonly disabled = input(false);
+  readonly ariaLabel = input<string>('Carrito de compras');
+
+  protected readonly hasQuantity = computed(() => {
+    const q = this.quantity();
+    return q !== null && q !== undefined && q > 0;
+  });
+}