Enhance styling and structure of custom fields in product templates

- Updated SCSS styles for headers (h2, h3) and added bold styling for required custom fields.
- Improved layout with additional margin for attributes and ensured consistent font weights.
- Modified PHP template to include a clearer structure for custom fields, adding a note for required fields.

templates_user/shop-product/_partial/product-custom-fields.php

@@ -1,6 +1,7 @@
-<? if ( is_array( $this -> custom_fields ) ): foreach ( $this -> custom_fields as $custom_field ):?>
+<? if ( is_array( $this -> custom_fields ) ):?>
+  <? foreach ( $this -> custom_fields as $custom_field ):?>
   <div class="custom-field">
-    <div class="_name">
+    <div class="_name <? if ( !empty( $custom_field['is_required'] ) ): ?>bold<? endif; ?>">
       <?= $custom_field['name'];?><? if ( !empty( $custom_field['is_required'] ) ): ?>*<? endif; ?>:
     </div>
     <div class="_input">
@@ -9,4 +10,11 @@
       </div>
     </div>
   </div>
-<? endforeach; endif;?>
+  <? endforeach;?>
+  <div class="custom-field">
+    <div class="_name"></div>
+    <div class="_input">
+      * - pole wymagane
+    </div>
+  </div>
+<? endif;?>