Amortize LLM research cost across generated articles (v0.5.2)

Research LLM call runs once per pipeline but was logged with no run_id
or post_id, making it invisible in per-article cost breakdowns. Now the
pipeline's cost tracker flows through Source_Collector to the research
provider, tagging costs with the run_id. After all articles complete,
amortize_research_costs() divides the cost evenly and inserts one row
per article. link_generation_logs() excludes llm_research stage so the
first article doesn't grab the full cost.

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:           0.5.1
+ * Version:           0.5.2
  * 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', '0.5.1' );
+define( 'PRAUTOBLOGGER_VERSION', '0.5.2' );
 define( 'PRAUTOBLOGGER_DB_VERSION', '1.1.0' );
 define( 'PRAUTOBLOGGER_PLUGIN_FILE', __FILE__ );
 define( 'PRAUTOBLOGGER_PLUGIN_DIR', plugin_dir_path( __FILE__ ) );