fix: move Generate Now to background processing to avoid 120s timeout

Hostinger's LiteSpeed web server kills any HTTP connection that runs
longer than 120 seconds with a 500 "Request Timeout" error. The full
pipeline (Reddit fetch → topic scoring → article generation → editorial
pass → image gen ×2) takes 120-180s, causing "Request failed: error"
on every manual generation attempt.

Architecture change:
- Generate Now AJAX handler now schedules a one-shot WP-Cron event
  and returns immediately (~100ms response time)
- New prautoblogger_manual_generation cron action runs the pipeline
  in a separate PHP process free from the connection timeout
- Pipeline progress is written to a transient at each stage
- New prautoblogger_generation_status AJAX endpoint lets the frontend
  poll progress every 5 seconds
- Frontend auto-resumes polling on page load if a generation is running
- Direct wp-cron.php loopback ensures cron fires even if DISABLE_WP_CRON
  is set (common on Hostinger)

Version bump: 0.2.9 → 0.3.0

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

prautoblogger.php

@@ -8,7 +8,7 @@ declare(strict_types=1);
  * Plugin Name:       PRAutoBlogger
  * Plugin URI:        https://peptiderepo.com/prautoblogger
  * Description:       Monitors social media for trending topics, generates SEO-friendly blog posts using AI, and publishes them on a daily schedule with full cost tracking and self-improvement metrics.
- * Version:           0.2.9
+ * Version:           0.3.0
  * Requires at least: 6.0
  * Requires PHP:      7.4
  * Author:            PeptideRepo
@@ -35,7 +35,7 @@ if ( ! defined( 'ABSPATH' ) ) {
 | and limits without magic strings.
 */
 
-define( 'PRAUTOBLOGGER_VERSION', '0.2.9' );
+define( 'PRAUTOBLOGGER_VERSION', '0.3.0' );
 define( 'PRAUTOBLOGGER_DB_VERSION', '1.1.0' );
 define( 'PRAUTOBLOGGER_PLUGIN_FILE', __FILE__ );
 define( 'PRAUTOBLOGGER_PLUGIN_DIR', plugin_dir_path( __FILE__ ) );