Fix accessibility violations: color contrast, aside nesting

- Improve text contrast from #666/#888/#999 to #555/#6b6b6b across site (WCAG AA)
- Fix aside nesting in all 10 blog articles (aside→div in related-articles)
- Fix aside nesting in quote sidebar
- Update CRO enhancement CSS/JS inline colors

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

blog/articles/cost-of-manual-data-work-professional-services.php

@@ -81,14 +81,14 @@ include($_SERVER['DOCUMENT_ROOT'] . '/includes/nav.php');
 
         </div>
 
-            <aside class="related-articles">
+            <div class="related-articles">
                 <h2>Related Articles</h2>
                 <ul>
                     <li><a href="/blog/articles/due-diligence-automation-law-firms">How Law Firms Can Automate Due Diligence Document Review</a></li>
                     <li><a href="/blog/articles/research-automation-management-consultancy">Research Automation for Management Consultancies</a></li>
                     <li><a href="/blog/articles/document-extraction-pdf-to-database">Document Extraction: From Unstructured PDF to Structured Database</a></li>
                 </ul>
-            </aside>
+            </div>
         <footer class="article-footer">
             <p>Written by <strong>UK AI Automation</strong> — <a href="/quote">Get a Quote</a></p>
         </footer>