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/assets/ui/less/form.variables.less

@@ -0,0 +1,53 @@
+
+//
+// Forms
+// --------------------------------------------------
+
+@input-bg:                       #fff;
+@input-bg-disabled:              @gray-lighter;
+
+@input-color:                    #385487;
+@input-border:                   #d1d6d9;
+@input-border-focus:             @input-border;
+@input-border-radius:            3px;
+@input-border-fade:              fade(@input-border, 25%);
+@input-box-shadow:               ~"inset 0 1px 0 @{input-border-fade}, 0 1px 0 rgba(255,255,255,.5)";
+
+@input-color-placeholder:        #cccccc;
+@input-color-disabled:           #999999;
+
+@input-height-base:              (@line-height-computed + (@padding-base-vertical * 2) + 2);
+@input-height-large:             (ceil(@font-size-large * @line-height-large) + (@padding-large-vertical * 2) + 2);
+@input-height-small:             (floor(@font-size-small * @line-height-small) + (@padding-small-vertical * 2) + 2);
+
+@legend-color:                   @gray-dark;
+@legend-border-color:            #e5e5e5;
+
+@input-group-addon-bg:           @gray-lighter;
+@input-group-addon-border-color: @input-border;
+
+@label-font-size: @font-size-base - 1;
+@input-font-size: @font-size-base;
+@color-label:     #2A3E51;
+
+@input-transition: border-color ease-in-out .15s, box-shadow ease-in-out .15s;
+
+@form-breakpoint-min: 770px;
+@form-breakpoint-max: (@form-breakpoint-min - 1);
+
+@color-input-sidebar-control:                #C4C4C4;
+
+@color-form-field-border:                    @input-border;
+@color-form-field-border-focus:              @input-border-focus;
+@color-form-required-asterisk:               @brand-danger;
+@color-form-sidebar:                         #ecf0f1;
+@color-form-field-preview-bg:                #f6f6f6;
+@color-form-field-preview-text:              #555555;
+@color-form-field-bg:                        #ffffff;
+@color-form-field-icon:                      #bdbdbd;
+@color-help-block-text:                      #777777;
+
+@color-form-field-recordfinder-btn:          #333333;
+
+@color-form-checkboxlist-border:             #e2e2e2;
+@color-form-checkboxlist-background:         #FFFFFF;