Optimise /odoo-ia/ and fix the site-wide 'null' header bug

/odoo-ia/ (279 impressions at position 6.8 for 'odo ia', zero clicks):
- H1 answers the query instead of describing the page: 'Odoo IA: que hace la
  inteligencia artificial en Odoo (y que no)'.
- Hero stats '60+ Recursos / 85% Automatizacion / 24/7 Operacion' replaced with
  the three honest routes: nativo / integracion / fuera. '85%' had no source.
- 'Empieza por aqui': five curated entry points, so the hub is a guide and not
  only a list of 55 links.
- Hosting CTA with utm_medium=hub-cta and a disclosure.
- FAQ (5 questions) + matching FAQPage schema. Answers are conditional on
  version and edition; no feature list is asserted, because odoo.com has no AI
  page to verify one against.

Separately, a real defect found while checking the render: 1,714 script blocks
across 840 pages called document.write(null) or set innerHTML = null, so the
header and footer rendered the literal text 'null'. Replaced with
createHeader()/createFooter(), which restores the real navigation on every
affected page.

de/odoo-ia/odoo-ocr-ia-reconocimiento-documentos-2025/index.html

@@ -275,7 +275,7 @@
 </head>
 <body>
 <script src="/components/header.min.js"></script>
-<script>document.write(/*W6-static*/null);</script>
+    <script>document.write(createHeader());</script>
 <nav class="breadcrumbs">
 <a href="/">Startseite</a> › <a href="/de/odoo-ia/">Odoo KI</a> › <span>OCR KI Reconocimiento Documentos</span>
 </nav>
@@ -512,7 +512,7 @@
         }));
     </script>
 <script src="/components/footer.min.js"></script>
-<script>document.write(/*W6-static*/null);</script>
+    <script>document.write(createFooter());</script>
 <script src="/js/cookie-banner.min.js"></script>
 <!-- D3.js Library -->
 <script src="https://cdnjs.cloudflare.com/ajax/libs/d3/7.8.5/d3.min.js"></script>