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-builtin-functions/language-function-nocache.md

@@ -0,0 +1,20 @@
+# {nocache}
+
+`{nocache}` is used to disable caching of a template section. Every
+`{nocache}` must be paired with a matching `{/nocache}`.
+
+> **Note**
+>
+> Be sure any variables used within a non-cached section are also
+> assigned from PHP when the page is loaded from the cache.
+
+```smarty
+Today's date is
+{nocache}
+{$smarty.now|date_format}
+{/nocache}
+```
+   
+The above code will output the current date on a cached page.
+
+See also the [caching section](../../programmers/caching.md).