fix: resolve PHPCS errors — remove short ternaries and fix docblock placement

- Replace 4 short ternary operators (?:) with explicit conditionals in Cost_Tracker
- Move declare(strict_types=1) after file-level docblocks in 3 template files
  (PHPCS requires docblock immediately after opening PHP tag)

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

admin/partials/articles-list.php

@@ -1,11 +1,12 @@
 <?php
-declare( strict_types=1 );
 /**
  * Articles management partial.
  *
  * @since 1.0.0
  */
 
+declare( strict_types=1 );
+
 if ( ! defined( 'ABSPATH' ) ) {
 	exit;
 }