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/demo/pages/plugins.htm

@@ -0,0 +1,30 @@
+title = "Plugin components"
+url = "/demo/plugins"
+layout = "default"
+
+[demoTodo]
+max = 3
+==
+<div class="jumbotron title-js">
+    <div class="container">
+        <div class="row">
+            <div class="col-8">
+                <h1>Plugin components</h1>
+                <p>Plugins can provide components, simple building blocks that enrich any page or layout. Check out the todo example below.</p>
+            </div>
+        </div>
+    </div>
+</div>
+
+<div class="container">
+    {% component 'demoTodo' %}
+</div>
+
+<!-- Page Explanation -->
+<div class="container">{% partial "explain/plugins.htm" %}</div>
+
+<br />
+
+<div class="text-center">
+    <p><a target="_blank" href="https://wintercms.com/docs" class="btn btn-lg btn-default">Learn more at Winter's Documentation</a></p>
+</div>