feat: enhance product ticket selector and vertical cart card components

- Refactor ProductTicketSelectorComponent to improve variant selection logic and error handling.
- Introduce a new signal for variant attributes and manage variant loading more efficiently.
- Update the UI to reflect saving state in ProductVerticalWithCartCardComponent, preventing actions while saving.
- Adjust button text based on saving state for better user feedback.

src/app/shared/components/product-row-card/product-row-card.component.html

@@ -34,7 +34,9 @@
         <app-button variant="primary" (click)="onBuy()"> Comprar </app-button>
       </div>
       <div class="product-row-card__btn-wrapper">
-        <app-button variant="secondary" (click)="onAddToCart()"> Agregar al carrito </app-button>
+        <app-button variant="secondary" [disabled]="saving()" (click)="onAddToCart()">
+          {{ saving() ? 'Guardando' : 'Agregar al carrito' }}
+        </app-button>
       </div>
     </div>
   </div>

src/app/shared/components/product-row-card/product-row-card.component.ts

@@ -27,6 +27,7 @@ export class ProductRowCardComponent {
   readonly description = input<string>('');
   readonly price = input<number>(0);
   readonly variants = input<Variant[]>([]);
+  readonly saving = input(false);
 
   // Internal state models
   readonly quantity = model<number>(1);
@@ -51,6 +52,10 @@ export class ProductRowCardComponent {
   readonly formattedPrice = computed(() => this.formatCurrency(this.effectivePrice()));
 
   protected onAddToCart(): void {
+    if (this.saving()) {
+      return;
+    }
+
     this.addToCart.emit({
       quantity: this.quantity(),
       variant: this.selectedVariant(),