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-use-include-path.md

@@ -0,0 +1,49 @@
+\$use\_include\_path {#variable.use.include.path}
+====================
+
+This tells smarty to respect the
+[include\_path](https://www.php.net/ini.core.php#ini.include-path) within
+the [`File Template Resource`](#resources.file) handler and the plugin
+loader to resolve the directories known to
+[`$template_dir`](#variable.template.dir). The flag also makes the
+plugin loader check the include\_path for
+[`$plugins_dir`](#variable.plugins.dir).
+
+> **Note**
+>
+> You should not design your applications to rely on the include\_path,
+> as this may - depending on your implementation - slow down your system
+> (and Smarty) considerably.
+
+If use\_include\_path is enabled, file discovery for
+[`$template_dir`](#variable.template.dir) and
+[`$plugins_dir`](#variable.plugins.dir) work as follows.
+
+-   For each element `$directory` in array (\$template\_dir or
+    \$plugins\_dir) do
+
+-   Test if requested file is in `$directory` relative to the [current
+    working directory](https://www.php.net/function.getcwd.php). If file
+    found, return it.
+
+-   For each `$path` in include\_path do
+
+-   Test if requested file is in `$directory` relative to the `$path`
+    (possibly relative to the [current working
+    directory](https://www.php.net/function.getcwd.php)). If file found,
+    return it.
+
+-   Try default\_handler or fail.
+
+This means that whenever a directory/file relative to the current
+working directory is encountered, it is preferred over anything
+potentially accessible through the include\_path.
+
+> **Note**
+>
+> Smarty does not filter elements of the include\_path. That means a
+> \".:\" within your include path will trigger the current working
+> directory lookup twice.
+
+See also [`Template Resources`](#resources) and
+[`$template_dir`](#variable.template.dir)