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/svg-icons.less

@@ -0,0 +1,33 @@
+.svg-icon-container {
+    img.svg-icon {
+        // SVG icons are invisible until SVG support is detected
+        // with JavaScript to reduce flickering on page load.
+        // This should be overridden in a specific control,
+        // inside html.svg {}
+        display: none;
+    }
+
+    &.svg-active-effects {
+        img.svg-icon {
+            -webkit-filter: grayscale(100%);
+            filter: grayscale(100%);
+            .opacity(0.6);
+        }
+
+        &:hover, &.active {
+            img.svg-icon {
+                -webkit-filter: none;
+                filter: none;
+                .opacity(1);
+            }
+        }
+    }
+}
+
+html.svg {
+    .svg-icon-container {
+        i.svg-replace {
+            display: none;
+        }
+    }
+}