feat: enhance checkout process with purchase editing and status handling

- Implemented purchase editing functionality in CheckoutPageComponent, allowing users to modify items in their purchase.
- Added a new guard (checkoutPendingPurchaseGuard) to prevent navigation away from the checkout page while a purchase is in progress.
- Updated the login page to handle return URLs after authentication.
- Enhanced product detail page to support direct purchases with a new buyNow method.
- Introduced new UI elements and logic to handle purchase status, including expired and rejected states in PurchaseStatusPageComponent.
- Improved cart component to allow editing of item quantities with a toggle button.
- Added quantity selector enhancements to disable controls when necessary.
- Updated tests to cover new functionalities and ensure proper behavior of components.

src/app/shared/components/cart-item/cart-item.component.html

@@ -34,20 +34,25 @@
       }
     </div>
 
-    <div class="d-flex justify-content-end align-items-center mt-auto cart-item-actions">
-      <app-quantity-selector
-        size="small"
-        [quantity]="quantity()"
-        (quantityChange)="onQuantityChange($event)"
-        (increase)="onIncrease()"
-        (decrease)="onDecrease()"
-      />
-      <app-icon-button
-        variant="trash"
-        class="cart-item-remove-btn"
-        (click)="onRemove()"
-      />
-    </div>
+    @if (!readonly()) {
+      <div class="d-flex justify-content-end align-items-center mt-auto cart-item-actions">
+        <app-quantity-selector
+          size="small"
+          [quantity]="quantity()"
+          [disabled]="quantityDisabled()"
+          (quantityChange)="onQuantityChange($event)"
+          (increase)="onIncrease()"
+          (decrease)="onDecrease()"
+        />
+        @if (!quantityDisabled() && showRemove()) {
+          <app-icon-button
+            variant="trash"
+            class="cart-item-remove-btn"
+            (click)="onRemove()"
+          />
+        }
+      </div>
+    }
   </div>
 </article>