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

Bug 1: extract get_style_suffix() helper that treats '' as "use default", applied to all 3 call sites in class-image-prompt-builder.php.

Bug 2: thread $cost_tracker through ArticleWorker → Publisher → PostAssembler → ImagePipeline so image costs share the article's run_id in wp_prautoblogger_generation_log.

Version: 0.12.1 → 0.12.2
Reviewed-by: peptiderepo (CTO)
QA: qa-reviews/prautoblogger/2026-04-23-7669a9c1.md

CHANGELOG.md

@@ -5,6 +5,14 @@ All notable changes to PRAutoBlogger will be documented in this file.
 Format follows [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project uses [Semantic Versioning](https://semver.org/).
 
+## [0.12.2] — 2026-04-24
+
+### Fixed
+- **Image style suffix empty-string bypass** — `get_option()` for `prautoblogger_image_style_suffix` only returns the default constant when the key is absent from `wp_options`; an empty string stored in the DB returns `''`, bypassing fallback entirely. Root cause of post #675 rendering photorealistically instead of as a newspaper comic. Fixed all three call sites in `class-image-prompt-builder.php` (lines 85, 107, 272) by extracting a private helper `get_style_suffix()` that treats both absent AND empty string as "use default".
+
+- **Image cost logged under wrong run_id** — `class-image-pipeline.php` created a fresh cost tracker when invoked without an argument, so image costs were logged under a different `run_id` than the article's other stages. Cost breakdowns aggregating by `run_id` silently excluded the image line item. Fixed by threading the article worker's cost tracker through `PRAutoBlogger_Publisher` and `PRAutoBlogger_Post_Assembler::attach_generated_images()` to the image pipeline constructor. Image costs now share the same `run_id` as analysis, draft, review, and llm_research stages.
+
+
 ## [0.12.1] — 2026-04-23
 
 ### Fixed