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/assets/less/elements/callouts.less

@@ -0,0 +1,50 @@
+//
+// Callouts
+// --------------------------------------------------
+
+.callout {
+    margin-bottom: @line-height-computed;
+    padding: @callout-padding;
+    border-left: 3px solid @callout-border;
+    code, .highlight {
+    }
+    h4 {
+        margin-top: 0;
+        margin-bottom: 5px;
+    }
+    p:last-child {
+        margin-bottom: 0;
+    }
+}
+
+.callout-danger {
+    background-color: @callout-danger-bg;
+    border-color: @callout-danger-border;
+    h4 {
+        color: @callout-danger-text;
+    }
+}
+
+.callout-warning {
+    background-color: @callout-warning-bg;
+    border-color: @callout-warning-border;
+    h4 {
+        color: @callout-warning-text;
+    }
+}
+
+.callout-info {
+    background-color: @callout-info-bg;
+    border-color: @callout-info-border;
+    h4 {
+        color: @callout-info-text;
+    }
+}
+
+.callout-success {
+    background-color: @callout-success-bg;
+    border-color: @callout-success-border;
+    h4 {
+        color: @callout-success-text;
+    }
+}