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/index.md

@@ -0,0 +1,50 @@
+# Smarty 4 Documentation
+Smarty is a template engine for PHP, facilitating the separation of presentation (HTML/CSS) from application logic. 
+
+It allows you to write **templates**, using **variables**, **modifiers**, **functions** and **comments**, like this:
+```html
+<h1>{$title|escape}</h1>
+
+<p>
+    The number of pixels is: {math equation="x * y" x=$height y=$width}.
+</p>
+```
+
+When this template is rendered, with the value "Hello world" for the variable $title, 640 for $width, 
+and 480 for $height, the result is:
+```html
+<h1>Hello world</h1>
+
+<p>
+    The number of pixels is: 307200.
+</p>
+```
+
+## Introduction
+- [Philosophy](./philosophy.md) - or "Why do I need a template engine?"
+- [Features](./features.md) - or "Why do I want Smarty?"
+- [Getting Started](./getting-started.md)
+
+## Smarty for template designers
+- [Basic Syntax](designers/language-basic-syntax/index.md)
+- [Variables](designers/language-variables/index.md)
+- [Variable Modifiers](designers/language-modifiers/index.md)
+- [Combining Modifiers](./designers/language-combining-modifiers.md)
+- [Built-in Functions](designers/language-builtin-functions/index.md)
+- [Custom Functions](designers/language-custom-functions/index.md)
+- [Config Files](./designers/config-files.md)
+- [Debugging Console](./designers/chapter-debugging-console.md)
+
+## Smarty for php developers
+- [Charset Encoding](./programmers/charset.md)
+- [Constants](./programmers/smarty-constants.md)
+- [Smarty Class Variables](./programmers/api-variables.md)
+- [Smarty Class Methods](./programmers/api-functions.md)
+- [Caching](./programmers/caching.md)
+- [Resources](./programmers/resources.md)
+- [Advanced Features](./programmers/advanced-features.md)
+- [Extending Smarty With Plugins](./programmers/plugins.md)
+
+## Other
+- [Some random tips & tricks](./appendixes/tips.md)
+- [Troubleshooting](./appendixes/troubleshooting.md)