feat(widgets): reviews + highlights carousel cards; plate-aware board list

Add zibll reviews/highlights marketing widgets with CSS, and make the
legacy forum board-list widget prefer aksrt_forum_plate CPT.

assets/css/frontend/widgets.css

@@ -4,3 +4,4 @@
 @import url("widgets/part-4.css");
 @import url("widget-slider.css");
 @import url("widget-batch3.css");
+@import url("widget-batch3c.css");