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-cat.md

@@ -0,0 +1,36 @@
+# cat
+
+This value is concatenated to the given variable.
+
+## Basic usage
+```smarty
+{$myVar|cat:' units'}
+```
+
+## Parameters
+
+| Parameter | Type   | Required | Description                                      |
+|-----------|--------|----------|--------------------------------------------------|
+| 1         | string | No       | This value to concatenate to the given variable. |
+
+## Examples
+
+```php
+<?php
+
+    $smarty->assign('articleTitle', "Psychics predict world didn't end");
+
+```
+
+Where template is:
+
+```smarty
+    {$articleTitle|cat:' yesterday.'}
+```
+
+Will output:
+
+```
+    Psychics predict world didn't end yesterday.
+```
+