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-basic-syntax/index.md

@@ -0,0 +1,33 @@
+# Basic Syntax
+
+A simple Smarty template could look like this:
+```smarty
+<h1>{$title|escape}</h1>
+<ul>
+    {foreach $cities as $city}
+        <li>{$city.name|escape} ({$city.population})</li>
+    {foreachelse}
+        <li>no cities found</li>        
+    {/foreach}
+</ul>
+```
+
+All Smarty template tags are enclosed within delimiters. By default
+these are `{` and `}`, but they can be
+[changed](../../programmers/api-variables/variable-left-delimiter.md).
+
+For the examples in this manual, we will assume that you are using the
+default delimiters. In Smarty, all content outside of delimiters is
+displayed as static content, or unchanged. When Smarty encounters
+template tags, it attempts to interpret them, and displays the
+appropriate output in their place.
+
+The basis components of the Smarty syntax are:
+
+- [Comments](language-syntax-comments.md)
+- [Variables](language-syntax-variables.md)
+- [Functions](language-syntax-functions.md)
+- [Attributes](language-syntax-attributes.md)
+- [Quotes](language-syntax-quotes.md)
+- [Math](language-math.md)
+- [Escaping](language-escaping.md)