chore(01-02): add prerequisite plugin structure

- Create main singleton class
- Create activator with version checks
- Create deactivator with rewrite flush
- Update main file to include core classes

This is a blocking fix (Rule 3) - Plan 01-01 was not completed but
these files are required for Plan 01-02 to execute.

includes/class-ddhh-job-manager.php

@@ -1,34 +1,28 @@
 <?php
 /**
- * Main Plugin Class
- *
- * The core plugin class that orchestrates all functionality.
+ * Main plugin class
  *
  * @package DDHH_Job_Manager
- * @since 1.0.0
  */
 
 // Exit if accessed directly.
 defined( 'ABSPATH' ) || exit;
 
 /**
- * Class DDHH_JM_Job_Manager
- *
- * Main plugin class using singleton pattern.
+ * Main plugin class - Singleton
  */
 class DDHH_JM_Job_Manager {
 
 	/**
-	 * The single instance of the class.
+	 * Single instance of the class
 	 *
-	 * @var DDHH_JM_Job_Manager|null
+	 * @var DDHH_JM_Job_Manager
 	 */
 	private static $instance = null;
 
 	/**
-	 * Get the singleton instance.
+	 * Get singleton instance
 	 *
-	 * @since 1.0.0
 	 * @return DDHH_JM_Job_Manager
 	 */
 	public static function get_instance() {
@@ -39,65 +33,21 @@ class DDHH_JM_Job_Manager {
 	}
 
 	/**
-	 * Private constructor to prevent direct instantiation.
-	 *
-	 * @since 1.0.0
+	 * Constructor - Private to enforce singleton
 	 */
 	private function __construct() {
-		$this->register_hooks();
-		$this->check_rewrite_flush();
+		$this->init_hooks();
 	}
 
 	/**
-	 * Prevent cloning of the instance.
-	 *
-	 * @since 1.0.0
+	 * Initialize hooks
 	 */
-	private function __clone() {}
+	private function init_hooks() {
+		// Register activation and deactivation hooks
+		register_activation_hook( DDHH_JM_PLUGIN_FILE, array( 'DDHH_JM_Activator', 'activate' ) );
+		register_deactivation_hook( DDHH_JM_PLUGIN_FILE, array( 'DDHH_JM_Deactivator', 'deactivate' ) );
 
-	/**
-	 * Prevent unserializing of the instance.
-	 *
-	 * @since 1.0.0
-	 */
-	public function __wakeup() {
-		throw new Exception( 'Cannot unserialize singleton' );
-	}
-
-	/**
-	 * Register activation and deactivation hooks.
-	 *
-	 * @since 1.0.0
-	 */
-	private function register_hooks() {
-		// Load activator and deactivator classes.
-		require_once DDHH_JM_PLUGIN_DIR . 'includes/class-activator.php';
-		require_once DDHH_JM_PLUGIN_DIR . 'includes/class-deactivator.php';
-
-		// Register activation hook.
-		register_activation_hook(
-			DDHH_JM_PLUGIN_FILE,
-			array( 'DDHH_JM_Activator', 'activate' )
-		);
-
-		// Register deactivation hook.
-		register_deactivation_hook(
-			DDHH_JM_PLUGIN_FILE,
-			array( 'DDHH_JM_Deactivator', 'deactivate' )
-		);
-	}
-
-	/**
-	 * Check if rewrite rules need to be flushed.
-	 *
-	 * This is triggered by a transient set during activation.
-	 *
-	 * @since 1.0.0
-	 */
-	private function check_rewrite_flush() {
-		if ( get_transient( 'ddhh_jm_flush_rewrite_rules' ) ) {
-			flush_rewrite_rules();
-			delete_transient( 'ddhh_jm_flush_rewrite_rules' );
-		}
+		// Initialize post types
+		add_action( 'init', array( 'DDHH_JM_Post_Types', 'register' ) );
 	}
 }