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/api-variables/variable-direct-access-security.md

@@ -0,0 +1,13 @@
+\$direct\_access\_security {#variable.direct.access.security}
+==========================
+
+Direct access security inhibits direct browser access to compiled or
+cached template files.
+
+Direct access security is enabled by default. To disable it set
+`$direct_access_security` to FALSE.
+
+> **Note**
+>
+> This is a compile time option. If you change the setting you must make
+> sure that the templates get recompiled.