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/vendor/bootstrap/less/mixins/labels.less

@@ -0,0 +1,12 @@
+// Labels
+
+.label-variant(@color) {
+  background-color: @color;
+
+  &[href] {
+    &:hover,
+    &:focus {
+      background-color: darken(@color, 10%);
+    }
+  }
+}