Dev-Umgebung: Kompatibilität für PHP 8.3 + Smarty 4.5.6

- Smarty 4.1.1 → 4.5.6 (behebt dynamic property deprecations)
- Core-Klassen: #[\AllowDynamicProperties] für Admin_role, base, Config,
  Customer, Customer_group, CustomerGroups, Item, Structure, website
- website.class.php: counts[parent_id] initialisieren vor ++ (PHP 8.1)
- layout.class.php: HTTP_ACCEPT_LANGUAGE mit isset-Guard
- website_init.php: session_status()-Check vor session_start
- .htaccess: HTTPS-Redirect via X-Forwarded-Proto (statt SERVER_PORT)
- themes/easyshop_advanced/media/: Parent-Theme-Assets nachgezogen
- .gitignore: smarty.4.1.1.bak ausschließen

libs/smarty/docs/programmers/api-functions/api-register-cacheresource.md

@@ -0,0 +1,40 @@
+registerCacheResource()
+
+dynamically register CacheResources
+
+Description
+===========
+
+void
+
+registerCacheResource
+
+string
+
+name
+
+Smarty\_CacheResource
+
+resource\_handler
+
+Use this to dynamically register a [CacheResource
+plugin](#caching.custom) with Smarty. Pass in the `name` of the
+CacheResource and the object extending Smarty\_CacheResource. See
+[Custom Cache Implementation](#caching.custom) for more information on
+how to create custom CacheResources.
+
+> **Note**
+>
+> In Smarty2 this used to be a callback function called
+> `$cache_handler_func`. Smarty3 replaced this callback by the
+> `Smarty_CacheResource` module.
+
+
+    <?php
+    $smarty->registerCacheResource('mysql', new Smarty_CacheResource_Mysql());
+    ?>
+
+       
+
+See also [`unregisterCacheResource()`](#api.unregister.cacheresource)
+and the [Custom CacheResource Implementation](#caching.custom) section.