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/mediamanager/partials/_item-sidebar-preview.php

@@ -0,0 +1,50 @@
+<div data-control="media-preview-container"></div>
+
+<script type="text/template" data-control="audio-template">
+    <div class="panel no-padding-bottom">
+        <audio src="{src}" controls>
+            <div class="media-player-fallback panel-embedded">Your browser doesn't support HTML5 audio.</div>
+        </audio>
+    </div>
+</script>
+
+<script type="text/template" data-control="video-template">
+    <video src="{src}" controls poster="<?= Url::asset('modules/backend/widgets/mediamanager/assets/images/video-poster.png') ?>">
+        <div class="panel media-player-fallback">Your browser doesn't support HTML5 video.</div>
+    </video>
+</script>
+
+<script type="text/template" data-control="image-template">
+    <div class="sidebar-image-placeholder-container"><div class="sidebar-image-placeholder" data-path="{path}" data-last-modified="{last-modified}" data-loading="true" data-control="sidebar-thumbnail"></div></div>
+</script>
+
+<script type="text/template" data-control="document-template">
+    <div class="sidebar-document-placeholder-container"><div class="sidebar-document-placeholder" data-path="{path}" data-last-modified="{last-modified}" data-control="sidebar-document"></div></div>
+</script>
+
+<script type="text/template" data-control="no-selection-template">
+    <div class="sidebar-image-placeholder-container">
+        <div class="sidebar-image-placeholder no-border">
+            <i class="icon-crop"></i>
+            <p><?= e(trans('backend::lang.media.nothing_selected')) ?></p>
+        </div>
+    </div>
+</script>
+
+<script type="text/template" data-control="multi-selection-template">
+    <div class="sidebar-image-placeholder-container">
+        <div class="sidebar-image-placeholder no-border">
+            <i class="icon-asterisk"></i>
+            <p><?= e(trans('backend::lang.media.multiple_selected')) ?></p>
+        </div>
+    </div>
+</script>
+
+<script type="text/template" data-control="go-up">
+    <div class="sidebar-image-placeholder-container">
+        <div class="sidebar-image-placeholder no-border">
+            <i class="icon-level-up"></i>
+            <p><?= e(trans('backend::lang.media.return_to_parent')) ?></p>
+        </div>
+    </div>
+</script>