feat(seo): add local business address and area served signals

- add PostalAddress and areaServed (Malaga city + province) to the
  sitewide JSON-LD structured data
- show the same address as visible NAP text in the footer and on the
  contact page, matching the schema exactly
- add address and area served to llms.txt for AEO/AI-crawler readability

src/components/SiteFooter.astro

@@ -20,6 +20,7 @@ const whatsappAriaLabel = 'Contactar con MNQ por WhatsApp';
         <div style="display:flex;flex-direction:column;gap:0.35rem;margin-top:var(--space-4);">
           <a href="tel:+34678171513" class="footer-link" style="width:fit-content;">+34 678 17 15 13</a>
           <a href="https://www.mnqcatering.com" class="footer-link" style="width:fit-content;">www.mnqcatering.com</a>
+          <p class="text-body-sm" style="width:fit-content;">Calle Camino Vivero, 6, 29014, Málaga</p>
         </div>
       </div>