[FUNCTIONAL] Add sync guard to prevent plugin loading during file sync

includes/class-wp-allstars-sync-guard.php

@@ -0,0 +1,60 @@
+<?php
+/**
+ * WP ALLSTARS Sync Guard
+ *
+ * Prevents plugin loading during sync operations to avoid fatal errors.
+ *
+ * @package WP_ALLSTARS
+ * @since 0.2.3.1
+ */
+
+if (!defined('ABSPATH')) {
+    exit;
+}
+
+/**
+ * Class responsible for detecting sync operations and preventing plugin loading
+ */
+class WP_Allstars_Sync_Guard {
+
+    /**
+     * Flag file name for sync operations
+     */
+    const SYNC_FLAG_FILE = '.syncing';
+
+    /**
+     * Check if sync is in progress
+     *
+     * @return bool Whether sync is in progress
+     */
+    public static function is_sync_in_progress() {
+        $flag_file = plugin_dir_path(dirname(__FILE__)) . self::SYNC_FLAG_FILE;
+        return file_exists($flag_file);
+    }
+
+    /**
+     * Handle sync mode by showing admin notice and preventing plugin loading
+     *
+     * @return bool True if sync is in progress, false otherwise
+     */
+    public static function handle_sync_mode() {
+        if (self::is_sync_in_progress()) {
+            // Add admin notice
+            add_action('admin_notices', array(__CLASS__, 'display_sync_notice'));
+            
+            // Return true to indicate plugin should not continue loading
+            return true;
+        }
+        
+        return false;
+    }
+    
+    /**
+     * Display sync in progress notice
+     */
+    public static function display_sync_notice() {
+        echo '<div class="notice notice-warning is-dismissible">';
+        echo '<p><strong>WP Allstars:</strong> Plugin files are currently syncing. The plugin functionality is temporarily disabled to prevent errors. Please try again in a moment.</p>';
+        echo '</div>';
+    }
+}