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-variables/variable-config-dir.md

@@ -0,0 +1,23 @@
+\$config\_dir {#variable.config.dir}
+=============
+
+This is the directory used to store [config files](#config.files) used
+in the templates. Default is `./configs`, meaning that Smarty will look
+for the `configs/` directory in the same directory as the executing php
+script.
+
+> **Note**
+>
+> It is not recommended to put this directory under the web server
+> document root.
+
+> **Note**
+>
+> As of Smarty 3.1 the attribute \$config\_dir is no longer accessible
+> directly. Use [`getConfigDir()`](#api.get.config.dir),
+> [`setConfigDir()`](#api.set.config.dir) and
+> [`addConfigDir()`](#api.add.config.dir) instead.
+
+See also [`getConfigDir()`](#api.get.config.dir),
+[`setConfigDir()`](#api.set.config.dir) and
+[`addConfigDir()`](#api.add.config.dir).