fix(phpcs): remove strict_types declaration that breaks file header order

PSR12.Files.FileHeader.IncorrectOrder requires the docblock immediately
after the opening PHP tag. The declare(strict_types=1) was inserted
between them.

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

admin/class-peptide-news-admin.php

@@ -1,5 +1,4 @@
 <?php
-declare( strict_types=1 );
 /**
  * Admin-specific functionality.
  *