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/designers/language-modifiers/language-modifier-lower.md

@@ -0,0 +1,34 @@
+# lower
+
+This is used to lowercase a variable. This is equivalent to the PHP
+[`strtolower()`](https://www.php.net/strtolower) function.
+
+## Basic usage
+```smarty
+{$myVar|lower}
+```
+
+## Examples
+
+```php
+<?php
+
+$smarty->assign('articleTitle', 'Two Convicts Evade Noose, Jury Hung.');
+```
+
+Where template is:
+
+```smarty
+{$articleTitle}
+{$articleTitle|lower}
+```
+
+This will output:
+
+```
+Two Convicts Evade Noose, Jury Hung.
+two convicts evade noose, jury hung.
+```
+       
+See also [`upper`](language-modifier-upper.md) and
+[`capitalize`](language-modifier-capitalize.md).