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

modules/backend/assets/less/controls/panels.less

@@ -0,0 +1,77 @@
+div.panel {
+    @panel-border-color: #e8eaeb;
+
+    padding: 20px;
+
+    &.no-padding {
+        padding: 0;
+    }
+
+    &.no-padding-bottom {
+        padding-bottom: 0;
+    }
+
+    &.padding-top {
+        padding-top: 20px;
+    }
+
+    &.padding-less {
+        padding: 15px;
+    }
+
+    &.transparent {
+        background: transparent;
+    }
+
+    &.border-left {
+        border-left: 1px solid @panel-border-color;
+    }
+
+    &.border-right {
+        border-right: 1px solid @panel-border-color;
+    }
+
+    &.border-bottom {
+        border-bottom: 1px solid @panel-border-color;
+    }
+
+    &.border-top {
+        border-top: 1px solid @panel-border-color;
+    }
+
+    &.triangle-down {
+        position: relative;
+
+        &:after {
+            .triangle(down, 15px, 8px, white);
+            position: absolute;
+            left: 15px;
+            bottom: -8px;
+            z-index: 101;
+        }
+
+        &:before {
+            .triangle(down, 17px, 9px, #e8eaeb);
+            position: absolute;
+            left: 14px;
+            bottom: -9px;
+            z-index: 100;
+        }
+    }
+
+    /*
+     * Panel sections
+     */
+
+    h3.section, > label {
+        text-transform: uppercase;
+        color: #95a5a6;
+        font-size: 13px;
+        font-weight: 600;
+        margin: 0 0 15px 0;
+    }
+
+    > label {
+        margin-bottom: 5px;
+    }
+}