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/programmers/charset.md

@@ -0,0 +1,44 @@
+Charset Encoding {#charset}
+================
+
+Charset Encoding {#charset.encoding}
+================
+
+There are a variety of encodings for textual data, ISO-8859-1 (Latin1)
+and UTF-8 being the most popular. Unless you change `Smarty::$_CHARSET`, 
+Smarty recognizes `UTF-8` as the internal charset if 
+[Multibyte String](https://www.php.net/mbstring) is available, 
+`ISO-8859-1` if not.
+
+> **Note**
+>
+> `ISO-8859-1` has been PHP\'s default internal charset since the
+> beginning. Unicode has been evolving since 1991. Since then it has
+> become the one charset to conquer them all, as it is capable of
+> encoding most of the known characters even across different character
+> systems (latin, cyrillic, japanese, ...). `UTF-8` is unicode\'s most
+> used encoding, as it allows referencing the thousands of character
+> with the smallest size overhead possible.
+>
+> Since unicode and UTF-8 are very wide spread nowadays, their use is
+> strongly encouraged.
+
+> **Note**
+>
+> Smarty\'s internals and core plugins are truly UTF-8 compatible since
+> Smarty 3.1. To achieve unicode compatibility, the [Multibyte
+> String](https://www.php.net/mbstring) PECL is required. Unless your PHP
+> environment offers this package, Smarty will not be able to offer
+> full-scale UTF-8 compatibility.
+
+
+    // use japanese character encoding
+    if (function_exists('mb_internal_charset')) {
+      mb_internal_charset('EUC-JP');
+    }
+
+    require_once 'libs/Smarty.class.php';
+    Smarty::$_CHARSET = 'EUC-JP';
+    $smarty = new Smarty();
+      
+