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/thumbnails.less

@@ -0,0 +1,36 @@
+//
+// Thumbnails
+// --------------------------------------------------
+
+
+// Mixin and adjust the regular image class
+.thumbnail {
+  display: block;
+  padding: @thumbnail-padding;
+  margin-bottom: @line-height-computed;
+  line-height: @line-height-base;
+  background-color: @thumbnail-bg;
+  border: 1px solid @thumbnail-border;
+  border-radius: @thumbnail-border-radius;
+  .transition(border .2s ease-in-out);
+
+  > img,
+  a > img {
+    &:extend(.img-responsive);
+    margin-left: auto;
+    margin-right: auto;
+  }
+
+  // Add a hover state for linked versions only
+  a&:hover,
+  a&:focus,
+  a&.active {
+    border-color: @link-color;
+  }
+
+  // Image captions
+  .caption {
+    padding: @thumbnail-caption-padding;
+    color: @thumbnail-caption-color;
+  }
+}