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/widgets/form/partials/_field_checkbox.php

@@ -0,0 +1,23 @@
+<!-- Checkbox -->
+<div class="checkbox custom-checkbox" tabindex="0">
+    <input
+        type="hidden"
+        name="<?= $field->getName() ?>"
+        value="0"
+        <?= $this->previewMode ? 'disabled="disabled"' : '' ?>>
+    <input
+        type="checkbox"
+        id="<?= $field->getId() ?>"
+        name="<?= $field->getName() ?>"
+        value="1"
+        <?= $this->previewMode ? 'disabled="disabled"' : '' ?>
+        <?= $field->isSelected() ? 'checked="checked"' : '' ?>
+        <?= $field->getAttributes() ?>>
+
+    <label for="<?= $field->getId() ?>">
+        <?= e(trans($field->label)) ?>
+    </label>
+    <?php if ($field->comment): ?>
+        <p class="help-block"><?= $field->commentHtml ? trans($field->comment) : e(trans($field->comment)) ?></p>
+    <?php endif ?>
+</div>