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-to-charset.md

@@ -0,0 +1,20 @@
+# to_charset
+
+`to_charset` is used to transcode a string from the internal charset to
+a given charset. This is the exact opposite of the [from_charset
+modifier](#language.modifier.from_charset).
+
+## Parameters
+
+| Parameter Position | Type   | Required | Possible Values                                                                                                              | Default      | Description                                                 |
+|--------------------|--------|----------|------------------------------------------------------------------------------------------------------------------------------|--------------|-------------------------------------------------------------|
+| 1                  | string | No       | `ISO-8859-1`, `UTF-8`, and any character set supported by [`mb_convert_encoding()`](https://www.php.net/mb_convert_encoding) | `ISO-8859-1` | The charset encoding the value is supposed to be encoded to |
+
+> **Note**
+>
+> Charset encoding should be handled by the application itself. This
+> modifier should only be used in cases where the application cannot
+> anticipate that a certain string is required in another encoding.
+
+See also [Charset Encoding](../../programmers/charset.md), [from_charset
+modifier](language-modifier-from-charset.md).