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/system/classes/ModelBehavior.php

@@ -0,0 +1,41 @@
+<?php namespace System\Classes;
+
+use Lang;
+use ApplicationException;
+use Winter\Storm\Database\ModelBehavior as ModelBehaviorBase;
+
+/**
+ * Base class for model behaviors.
+ *
+ * @package winter\wn-system-module
+ * @author Alexey Bobkov, Samuel Georges
+ */
+class ModelBehavior extends ModelBehaviorBase
+{
+    /**
+     * @var array Properties that must exist in the model using this behavior.
+     */
+    protected $requiredProperties = [];
+
+    /**
+     * Constructor
+     * @param Winter\Storm\Database\Model $model The extended model.
+     */
+    public function __construct($model)
+    {
+        parent::__construct($model);
+
+        /*
+         * Validate model properties
+         */
+        foreach ($this->requiredProperties as $property) {
+            if (!isset($model->{$property})) {
+                throw new ApplicationException(Lang::get('system::lang.behavior.missing_property', [
+                    'class' => get_class($model),
+                    'property' => $property,
+                    'behavior' => get_called_class()
+                ]));
+            }
+        }
+    }
+}