feat(widgets): oneline posts scroller + tilt showcase cases

Add remaining high-traffic zibll marketing widgets: horizontal posts
rail and left-copy/right-image tilt cases, with CSS registration.

assets/css/frontend/widgets.css

@@ -7,3 +7,4 @@
 @import url("widget-batch3c.css");
 @import url("widget-batch3d.css");
 @import url("widget-batch3e.css");
+@import url("widget-batch3f.css");