feat: VivesPOS landing on Winter CMS 1.2 — theme + plugin + Dockerfile

- Base: wintercms/winter branch 1.2 (full framework)
- Theme vivespos: Canvas 7 + Bootstrap 5 CDN, custom CSS
- Layout: deferred GTM/GA4 tracking, JSON-LD SoftwareApplication
- Partials: hero (offline-first), features, modes (offline/nube toggle),
  screenshots, pricing (3 planes), comparison, FAQ, CTA
- Plugin VivesPOS.Site with ContactForm
- Dockerfile: PHP 8.2 Apache, port 80, healthcheck
- Added winter/wn-pages, blog, sitemap, seo plugins
- Active theme set to vivespos

themes/vivespos/partials/home/cta.htm

@@ -0,0 +1,19 @@
+description = "CTA final — gradient brand, WhatsApp"
+==
+<section id="cta" class="py-5 py-md-6 bg-gradient-brand">
+  <div class="container text-center">
+    <h2 class="display-5 fw-bold text-white mb-3">Empieza a vender con VivesPOS hoy</h2>
+    <p class="lead text-white-50 mb-4">Descarga la version gratuita o agenda una demo con un especialista. Sin compromisos, sin spam, sin tarjeta de credito.</p>
+    <div class="row justify-content-center g-3">
+      <div class="col-md-5 col-lg-3">
+        <a href="https://wa.me/523317025248?text=Hola%2C%20quiero%20una%20demo%20de%20VivesPOS" class="btn btn-lg btn-light w-100 fw-semibold" target="_blank" rel="noopener">
+          <i class="bi-whatsapp me-2 text-success"></i>Agendar demo gratuita
+        </a>
+      </div>
+      <div class="col-md-5 col-lg-3">
+        <a href="#precios" class="btn btn-lg btn-outline-light w-100 fw-semibold">Ver planes y precios</a>
+      </div>
+    </div>
+    <p class="text-white-50 small mt-4 mb-0">Sin spam &middot; Sin compromisos &middot; Respuesta en menos de 2 horas en horario habil</p>
+  </div>
+</section>