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/ui/js/index.js

@@ -0,0 +1,34 @@
+import * as Vue from 'vue';
+import BackendAjaxHandler from './ajax/Handler';
+import BackendUiEventHandler from './ui/EventHandler';
+import BackendUiWidgetHandler from './ui/WidgetHandler';
+
+if (window.Snowboard === undefined) {
+    throw new Error('Snowboard must be loaded in order to use the Backend UI.');
+}
+
+((Snowboard) => {
+    Snowboard.addPlugin('backend.ajax.handler', BackendAjaxHandler);
+    Snowboard.addPlugin('backend.ui.eventHandler', BackendUiEventHandler);
+    Snowboard.addPlugin('backend.ui.widgetHandler', BackendUiWidgetHandler);
+
+    // Add the pre-filter immediately
+    Snowboard['backend.ajax.handler']().addPrefilter();
+
+    // Add polyfill for AssetManager
+    window.AssetManager = {
+        load: (assets, callback) => {
+            Snowboard.assetLoader().load(assets).then(
+                () => {
+                    if (callback && typeof callback === 'function') {
+                        callback();
+                    }
+                },
+            );
+        },
+    };
+    window.assetManager = window.AssetManager;
+})(window.Snowboard);
+
+// Add Vue to global scope
+window.Vue = Vue;