fix: Poprawki dataLayer GA4 — purchase price, format kluczy, fałszywa konwersja GADS

- purchase: id→item_id (string), name→item_name, price fallback na price_brutto gdy brak promo, user_data poza ecommerce
- begin_checkout: id→item_id, name→item_name, dodano google_business_vertical
- Usunięto fałszywą konwersję GADS (gtag conversion) ze strony checkout
- view_item: dodano currency PLN, price jako number zamiast string
- Dodano event view_cart na stronie koszyka
- add_to_cart: quantity parseInt zamiast string

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

templates_user/shop-basket/basket.php

@@ -33,6 +33,35 @@
     </div>
   <? endif; ?>
 </div>
+<? if ( $this -> settings['google_tag_manager_id'] && is_array( $this -> basket ) && count( $this -> basket ) ):?>
+<script>
+  dataLayer.push({
+    event: "view_cart",
+    ecommerce: {
+      currency: "PLN",
+      value: <?= \Shared\Helpers\Helpers::normalize_decimal( \Domain\Basket\BasketCalculator::summaryPrice( $this -> basket, $this -> coupon ) );?>,
+      items: [
+        <?
+        $view_cart_items = '';
+        foreach ( $this -> basket as $position_hash => $position ):
+          $product = (new \Domain\Product\ProductRepository($GLOBALS['mdb']))->findCached( (int)$position['product-id'], $GLOBALS['lang_id'] );
+          $price_product = \Domain\Basket\BasketCalculator::calculateBasketProductPrice((float)$product['price_brutto_promo'], (float)$product['price_brutto'], $this->coupon, $position);
+          if ( $view_cart_items ) $view_cart_items .= ',';
+          $view_cart_items .= '{';
+          $view_cart_items .= '"item_id": "' . $product['id'] . '",';
+          $view_cart_items .= '"item_name": "' . $product['language']['name'] . '",';
+          $view_cart_items .= '"price": ' . \Shared\Helpers\Helpers::normalize_decimal( $price_product['price_new'] ) . ',';
+          $view_cart_items .= '"quantity": ' . (int)$position['quantity'] . ',';
+          $view_cart_items .= '"google_business_vertical": "retail"';
+          $view_cart_items .= '}';
+        endforeach;
+        echo $view_cart_items;
+        ?>
+      ]
+    }
+  });
+</script>
+<? endif;?>
 <script>
   (function(o, r, l, e, n) {
     o[l] = o[l] || [];