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-caching.md

@@ -0,0 +1,38 @@
+\$caching {#variable.caching}
+=========
+
+This tells Smarty whether or not to cache the output of the templates to
+the [`$cache_dir`](#variable.cache.dir). By default this is set to the
+constant Smarty::CACHING\_OFF. If your templates consistently generate
+the same content, it is advisable to turn on `$caching`, as this may
+result in significant performance gains.
+
+You can also have [multiple](#caching.multiple.caches) caches for the
+same template.
+
+-   A constant value of Smarty::CACHING\_LIFETIME\_CURRENT or
+    Smarty::CACHING\_LIFETIME\_SAVED enables caching.
+
+-   A value of Smarty::CACHING\_LIFETIME\_CURRENT tells Smarty to use
+    the current [`$cache_lifetime`](#variable.cache.lifetime) variable
+    to determine if the cache has expired.
+
+-   A value of Smarty::CACHING\_LIFETIME\_SAVED tells Smarty to use the
+    [`$cache_lifetime`](#variable.cache.lifetime) value at the time the
+    cache was generated. This way you can set the
+    [`$cache_lifetime`](#variable.cache.lifetime) just before
+    [fetching](#api.fetch) the template to have granular control over
+    when that particular cache expires. See also
+    [`isCached()`](#api.is.cached).
+
+-   If [`$compile_check`](#variable.compile.check) is enabled, the
+    cached content will be regenerated if any of the templates or config
+    files that are part of this cache are changed.
+
+-   If [`$force_compile`](#variable.force.compile) is enabled, the
+    cached content will always be regenerated.
+
+See also [`$cache_dir`](#variable.cache.dir),
+[`$cache_lifetime`](#variable.cache.lifetime),
+[`$cache_modified_check`](#variable.cache.modified.check),
+[`is_cached()`](#api.is.cached) and the [caching section](#caching).