Add plugin system and improve language handling

Add global and page-level plugin support Implement language-aware
content filtering Add month translations to language files Refactor date
formatting to use translations Move translation loading to plugin system
Improve content availability checks

app/plugins.php

@@ -0,0 +1,83 @@
+<?php
+
+// Plugin System - manages global and page-level plugins
+
+class PluginManager {
+    private array $loadedPlugins = [];
+    private array $globalPlugins = [];
+    
+    public function loadGlobalPlugins(array $config): void {
+        if (!isset($config['plugins']['enabled'])) return;
+        
+        $plugins = array_map('trim', explode(',', $config['plugins']['enabled']));
+        foreach ($plugins as $pluginName) {
+            if (!empty($pluginName)) {
+                $this->loadPlugin($pluginName, 'global');
+            }
+        }
+    }
+    
+    public function loadPagePlugins(?array $metadata): void {
+        if (!$metadata || !isset($metadata['plugins'])) return;
+        
+        $plugins = array_map('trim', explode(',', $metadata['plugins']));
+        foreach ($plugins as $pluginName) {
+            if (!empty($pluginName)) {
+                $this->loadPlugin($pluginName, 'page');
+            }
+        }
+    }
+    
+    private function loadPlugin(string $pluginName, string $scope): bool {
+        if (isset($this->loadedPlugins[$pluginName])) return true;
+        
+        $pluginName = basename($pluginName);
+        
+        $customPluginPath = __DIR__ . "/../custom/plugins/{$scope}/{$pluginName}.php";
+        $appPluginPath = __DIR__ . "/plugins/{$scope}/{$pluginName}.php";
+        
+        $pluginPath = file_exists($customPluginPath) ? $customPluginPath 
+            : (file_exists($appPluginPath) ? $appPluginPath : null);
+        
+        if (!$pluginPath) {
+            error_log("Plugin not found: {$pluginName} (scope: {$scope})");
+            return false;
+        }
+        
+        require_once $pluginPath;
+        
+        $this->loadedPlugins[$pluginName] = [
+            'path' => $pluginPath,
+            'scope' => $scope,
+            'loaded_at' => microtime(true)
+        ];
+        
+        if ($scope === 'global') {
+            $this->globalPlugins[] = $pluginName;
+        }
+        
+        return true;
+    }
+    
+    public function getLoadedPlugins(): array {
+        return array_keys($this->loadedPlugins);
+    }
+    
+    public function getGlobalPlugins(): array {
+        return $this->globalPlugins;
+    }
+    
+    public function isLoaded(string $pluginName): bool {
+        return isset($this->loadedPlugins[$pluginName]);
+    }
+    
+    public function getPluginInfo(string $pluginName): ?array {
+        return $this->loadedPlugins[$pluginName] ?? null;
+    }
+}
+
+$GLOBALS['pluginManager'] = new PluginManager();
+
+function getPluginManager(): PluginManager {
+    return $GLOBALS['pluginManager'];
+}