Adopt reusable CI standard (#30)

Squash-merged from claude/adopt-ci-20260616.

QA-approved; all CI checks green on 3b4e3f04.

Agent-Session: deploy-ci-rollout-news-plugin-2026-06-16

includes/class-peptide-news-fetcher.php

@@ -87,7 +87,7 @@ class Peptide_News_Fetcher {
 		$stored = 0;
 		foreach ( $articles as $article ) {
 			if ( $this->store_article( $article ) ) {
-				$stored++;
+				++$stored;
 			}
 		}