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-append-by-ref.md

@@ -0,0 +1,46 @@
+appendByRef()
+
+append values by reference
+
+Description
+===========
+
+void
+
+appendByRef
+
+string
+
+varname
+
+mixed
+
+var
+
+bool
+
+merge
+
+This is used to [`append()`](#api.append) values to the templates by
+reference.
+
+> **Note**
+>
+> With the introduction of PHP5, `appendByRef()` is not necessary for
+> most intents and purposes. `appendByRef()` is useful if you want a PHP
+> array index value to be affected by its reassignment from a template.
+> Assigned object properties behave this way by default.
+
+NOTE.PARAMETER.MERGE
+
+
+    <?php
+    // appending name/value pairs
+    $smarty->appendByRef('Name', $myname);
+    $smarty->appendByRef('Address', $address);
+    ?>
+
+       
+
+See also [`append()`](#api.append), [`assign()`](#api.assign) and
+[`getTemplateVars()`](#api.get.template.vars).