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

plugins/winter/demo/composer.json

@@ -0,0 +1,33 @@
+{
+    "name": "winter/demo-plugin",
+    "type": "winter-plugin",
+    "description": "Demo Winter CMS plugin",
+    "keywords": ["winter", "cms", "demo", "plugin"],
+    "license": "MIT",
+    "authors": [
+        {
+            "name": "Alexey Bobkov",
+            "email": "aleksey.bobkov@gmail.com",
+            "role": "Co-founder"
+        },
+        {
+            "name": "Samuel Georges",
+            "email": "daftspunky@gmail.com",
+            "role": "Co-founder"
+        }
+    ],
+    "require": {
+        "php": ">=5.4",
+        "composer/installers": "~1.0"
+    },
+    "autoload": {
+        "psr-4": {
+            "Winter\\Demo\\": ""
+        }
+    },
+    "extra": {
+        "branch-alias": {
+            "dev-master": "1.0-dev"
+        }
+    }
+}