fix(storefront): add missing placeholder image asset and onerror fallback

getMainImage() referenced /assets/images/placeholder.svg as the no-image
fallback, but src/assets/images/ never existed - any item with zero
photos rendered a browser broken-image icon instead of a placeholder.
Added the asset.

Also added an (error) handler (onImageError) on every dynamic <img> that
renders a user/admin-supplied URL (product card, cart line item, cart
payment QR code, product gallery main + thumbnails) so a 404'd/broken
image URL swaps to the shared placeholder instead of shipping broken.

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

@@ -1,7 +1,7 @@
 <article class="product-card" [class.product-card-compact]="appearance === 'compact'" (mouseenter)="preview.emit(item.itemID)">
   <a [routerLink]="['/product', item.itemID] | langRoute" class="product-link" (click)="onSelected($event)">
     <div class="product-image">
-      <img [src]="getMainImage(item)" [alt]="title || item.name" loading="lazy" decoding="async" width="300" height="300" />
+      <img [src]="getMainImage(item)" [alt]="title || item.name" loading="lazy" decoding="async" width="300" height="300" (error)="onImageError($event)" />
       @if (showDiscountBadge && item.discount > 0) {
         <div class="discount-badge" [attr.aria-label]="'common.discountLabel' | translate:{ value: item.discount }">-{{ item.discount }}%</div>
       }

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

@@ -4,7 +4,7 @@ import { RouterLink } from '@angular/router';
 import { Product } from '../../core/products/models/product-domain.model';
 import { LangRoutePipe } from '../../pipes/lang-route.pipe';
 import { TranslatePipe } from '../../i18n/translate.pipe';
-import { cleanDescription, getBadgeClass, getDiscountedPrice, getMainImage } from '../../utils/item.utils';
+import { cleanDescription, getBadgeClass, getDiscountedPrice, getMainImage, onImageError } from '../../utils/item.utils';
 
 const STOCK_LABEL_KEYS: Record<string, string> = {
   high: 'catalog.stockHigh',
@@ -56,6 +56,7 @@ export class ProductCardComponent {
   readonly getDiscountedPrice = getDiscountedPrice;
   readonly getBadgeClass = getBadgeClass;
   readonly cleanDescription = cleanDescription;
+  readonly onImageError = onImageError;
 
   onAddToCart(event: Event): void {
     this.addToCart.emit({ itemID: this.item.itemID, event });

src/app/features/website/product/components/product-gallery/product-gallery.component.html

@@ -31,7 +31,7 @@
       }
 
       @default {
-        <img [src]="media[selectedIndex].url" [alt]="media[selectedIndex].alt" loading="eager" decoding="async" />
+        <img [src]="media[selectedIndex].url" [alt]="media[selectedIndex].alt" loading="eager" decoding="async" (error)="onImageError($event)" />
       }
     }
   </div>
@@ -45,7 +45,7 @@
           } @else if (item.type !== 'image') {
             <span class="product-gallery-doc">{{ item.type }}</span>
           }
-          <img [src]="item.thumbnailUrl" [alt]="item.alt + ' ' + ($index + 1)" loading="lazy" decoding="async" />
+          <img [src]="item.thumbnailUrl" [alt]="item.alt + ' ' + ($index + 1)" loading="lazy" decoding="async" (error)="onImageError($event)" />
         </button>
       }
     </div>

src/app/features/website/product/components/product-gallery/product-gallery.component.ts

@@ -1,6 +1,6 @@
 import { ChangeDetectionStrategy, Component, EventEmitter, Input, Output } from '@angular/core';
 import { Product } from '../../../../../core/products/models/product-domain.model';
-import { getMainImage } from '../../../../../utils/item.utils';
+import { getMainImage, onImageError } from '../../../../../utils/item.utils';
 import { TranslatePipe } from '../../../../../i18n/translate.pipe';
 
 type ProductMediaType = 'image' | 'video' | 'pdf' | 'manual' | 'warranty';
@@ -22,6 +22,8 @@ interface GalleryMediaItem {
   changeDetection: ChangeDetectionStrategy.OnPush
 })
 export class ProductGalleryComponent {
+  readonly onImageError = onImageError;
+
   @Input({ required: true }) product!: Product;
   @Input() selectedIndex = 0;
 

src/app/pages/cart/cart.component.html

@@ -29,7 +29,7 @@
                (touchstart)="onSwipeStart(item.itemID, $event)">
             <div class="cart-item">
               <a [routerLink]="['/product', item.itemID] | langRoute" class="item-image">
-                <img [src]="getMainImage(item)" [alt]="itemName(item)" loading="lazy" />
+                <img [src]="getMainImage(item)" [alt]="itemName(item)" loading="lazy" (error)="onImageError($event)" />
               </a>
               
               <div class="item-info">
@@ -216,7 +216,7 @@
           @if (qrCodeUrl()) {
             <div class="qr-section">
               <div class="qr-wrapper">
-                <img [src]="qrCodeUrl()" [attr.alt]="'cart.paymentQrAlt' | translate" class="qr-code" />
+                <img [src]="qrCodeUrl()" [attr.alt]="'cart.paymentQrAlt' | translate" class="qr-code" (error)="onImageError($event)" />
                 <div class="scan-line"></div>
               </div>
             </div>

src/app/pages/cart/cart.component.ts

@@ -9,7 +9,7 @@ import { EMPTY, interval, of, Subscription } from 'rxjs';
 import { catchError, exhaustMap, take, timeout } from 'rxjs/operators';
 import { DeliverySelectorComponent } from '../../components/delivery-selector/delivery-selector.component';
 import { TelegramLoginComponent } from '../../components/telegram-login/telegram-login.component';
-import { getDiscountedPrice, getMainImage, trackByItemId, getBadgeClass, getTranslatedField } from '../../utils/item.utils';
+import { getDiscountedPrice, getMainImage, trackByItemId, getBadgeClass, getTranslatedField, onImageError } from '../../utils/item.utils';
 import { LangRoutePipe } from '../../pipes/lang-route.pipe';
 import { TranslatePipe } from '../../i18n/translate.pipe';
 import { TranslateService } from '../../i18n/translate.service';
@@ -255,6 +255,7 @@ export class CartComponent implements OnDestroy {
   }
 
   readonly getMainImage = getMainImage;
+  readonly onImageError = onImageError;
   readonly trackByItemId = trackByItemId;
   readonly getDiscountedPrice = getDiscountedPrice;
   readonly getBadgeClass = getBadgeClass;

src/app/utils/item.utils.ts

@@ -13,6 +13,15 @@ export function getMainImage(item: Item): string {
   return item.photos?.[0]?.url || '/assets/images/placeholder.svg';
 }
 
+const PLACEHOLDER_IMAGE = '/assets/images/placeholder.svg';
+
+/** Swaps a broken/404'd <img> src to the shared placeholder, once, to avoid an infinite error loop. */
+export function onImageError(event: Event): void {
+  const img = event.target as HTMLImageElement;
+  if (img.src.endsWith(PLACEHOLDER_IMAGE)) return;
+  img.src = PLACEHOLDER_IMAGE;
+}
+
 export function trackByItemId(_index: number, item: Item): number | string {
   return item.id || item.itemID;
 }