v2.6.0: Content backup/git versioning, plugin type system, docs update

New features:
- ContentBackup class with ZIP backup/restore and git versioning
- Admin backup & restore page (content-backup.twig) with git init/commit/log/restore
- Plugin type system: system (blue) vs content (green) with visual badges
- PluginAPIInterface + AdminPluginAPI for plugin architecture
- Essential plugin flag (cannot edit/deactivate/delete)

Improvements:
- Consolidated enabled_plugins config (removed plugins.enabled)
- Removed Analytics/Logging toggles from admin config page
- Fixed Dashboard plugin Twig comments rendered as text
- Updated 20 guide files (NL+EN): configuratie, plugins, plugin-development,
  core-classes, theme-json, layouts, scss-styling, admin-beheerder, nieuw-thema, architectuur
- Improved accessibility test script (grep -E, min/max checks)

Cleanup:
- Removed unused classes: ARIAComponents, AccessibilityManager, ContentSecurityPolicy, etc.
- Removed vendor packages: mustache/mustache, php-mqtt/client
- Removed old templates: logs.twig, statistics.twig (now plugins)
- Moved language files to language/ directory

Tests:
- Pentest: 30/30 passed, 0 vulnerabilities
- WCAG 2.1 AA: 25/25 passed, 100% compliance

cms/core/plugin/PluginManager.php

@@ -4,7 +4,7 @@ class PluginManager
 {
     private array $plugins = [];
     private string $pluginsPath;
-    private ?CMSAPI $api = null;
+    private $api = null;
     private array $enabledPlugins = [];
     private array $actions = [];
     private array $filters = [];
@@ -16,7 +16,7 @@ class PluginManager
         $this->loadPlugins();
     }
     
-    public function setAPI(CMSAPI $api): void
+    public function setAPI($api): void
     {
         $this->api = $api;
         
@@ -50,10 +50,6 @@ class PluginManager
                 $className = $pluginName;
                 if (class_exists($className)) {
                     $this->plugins[$pluginName] = new $className();
-                    
-                    if ($this->api && method_exists($this->plugins[$pluginName], 'setAPI')) {
-                        $this->plugins[$pluginName]->setAPI($this->api);
-                    }
 
                     // Auto-register hooks from plugin methods
                     $hookMethods = ['onPageLoad', 'onBeforeRender', 'onAfterRender', 'onSearch', 'onMenuBuild'];
@@ -193,4 +189,68 @@ class PluginManager
         }
         return $urls;
     }
+
+    /**
+     * Collect admin menu items from all enabled plugins that implement getAdminMenu().
+     * Each plugin returns [['route' => 'plugin-name/action', 'label' => 'Label', 'icon' => 'bi-icon']].
+     *
+     * @return array Admin menu items from all plugins
+     */
+    public function getAdminMenuItems(): array
+    {
+        $items = [];
+        foreach ($this->plugins as $pluginName => $plugin) {
+            if (method_exists($plugin, 'getAdminMenu')) {
+                $pluginItems = $plugin->getAdminMenu();
+                if (is_array($pluginItems)) {
+                    foreach ($pluginItems as $item) {
+                        $items[] = $item;
+                    }
+                }
+            }
+        }
+        return $items;
+    }
+
+    /**
+     * Dispatch an admin route to a plugin that handles it.
+     * Plugins implement handleAdminRoute(string $action): ?string (returns rendered HTML or null).
+     *
+     * @param string $pluginName Plugin name
+     * @param string $action Action/sub-route within the plugin
+     * @return string|null Rendered HTML, or null if plugin doesn't handle it
+     */
+    public function dispatchAdminRoute(string $pluginName, string $action): ?string
+    {
+        $plugin = $this->getPlugin($pluginName);
+        if ($plugin === null) {
+            return null;
+        }
+        if (method_exists($plugin, 'handleAdminRoute')) {
+            return $plugin->handleAdminRoute($action);
+        }
+        return null;
+    }
+
+    /**
+     * Find which plugin handles a given admin route.
+     *
+     * @param string $route The admin route (e.g. 'statistics' or 'statistics/details')
+     * @return array|null ['plugin' => name, 'action' => action] or null
+     */
+    public function resolveAdminRoute(string $route): ?array
+    {
+        foreach ($this->getAdminMenuItems() as $item) {
+            $itemRoute = $item['route'] ?? '';
+            // Check if the requested route starts with this plugin's route
+            if ($route === $itemRoute || str_starts_with($route, $itemRoute . '/')) {
+                $action = substr($route, strlen($itemRoute) + 1);
+                return [
+                    'plugin' => $item['plugin'] ?? '',
+                    'action' => $action,
+                ];
+            }
+        }
+        return null;
+    }
 }