Fix imageNames sorting to preserve descending timestamp order

- Add explicit sortedByDescending in ViewModel to ensure images
  are returned sorted by upload timestamp (newest first)
- Ensures sort order is preserved through Flow transformations
- Fixes #5013

Author: gabbyemsden

app/src/main/java/openfoodfacts/github/scrachx/openfood/features/product/view/photos/ProductPhotosViewModel.kt

@@ -36,6 +36,7 @@ class ProductPhotosViewModel @Inject constructor(
         .filterNotNull()
         .map { product ->
             ImageNameParser.extractImageNames(productsAPI.getProductImages(product.code))
+                .sortedByDescending { it.timestamp }  // Ensure explicit sorting
                 .map { it.value }
         }.stateIn(
             viewModelScope,