fix: image style suffix empty-string bypass and image cost run_id mismatch (v0.12.2)

Bug 1: Image style suffix empty-string bypass
- get_option() for prautoblogger_image_style_suffix returns empty string from DB instead of default
- Root cause of post #675 rendering photorealistically instead of newspaper comic
- Fixed by extracting private helper get_style_suffix() that treats both absent AND empty as default
- Applied to all three call sites in class-image-prompt-builder.php (lines 85, 107, 272)

Bug 2: Image cost logged under wrong run_id
- class-image-pipeline.php created fresh cost tracker when invoked without argument
- Image costs logged under different run_id than article's other stages
- Cost breakdowns aggregating by run_id silently excluded image line items
- Fixed by threading article worker's cost tracker through Publisher to image pipeline
- Modified publisher.php and post-assembler.php to accept and pass cost_tracker
- Updated article-worker.php to pass cost_tracker to publisher methods
- Image costs now share same run_id as analysis, draft, review, and llm_research stages

Version: 0.12.1 -> 0.12.2
CHANGELOG: Added comprehensive entry describing both fixes

prautoblogger.php

@@ -9,7 +9,7 @@
  * 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:           0.12.1
+ * Version:           0.12.2
  * Requires at least: 6.0
  * Requires PHP:      7.4
  * Author:            PeptideRepo
@@ -35,7 +35,7 @@ if ( ! defined( 'ABSPATH' ) ) {
 | Defined here so every file in the plugin can reference paths, versions,
 | and limits without magic strings.
 */
-define( 'PRAUTOBLOGGER_VERSION', '0.12.1' );
+define( 'PRAUTOBLOGGER_VERSION', '0.12.2' );
 define( 'PRAUTOBLOGGER_DB_VERSION', '1.1.0' );
 define( 'PRAUTOBLOGGER_PLUGIN_FILE', __FILE__ );
 define( 'PRAUTOBLOGGER_PLUGIN_DIR', plugin_dir_path( __FILE__ ) );