feat: add mobile layout preview

apps/nextjs/src/components/board/mobile/mobile-board.module.css

@@ -1,8 +1,9 @@
 .grid {
+  container-type: inline-size;
   display: grid;
   grid-template-columns: repeat(var(--mobile-column-count), minmax(0, 1fr));
   grid-auto-flow: row;
-  grid-auto-rows: min(calc((100vw - 42px) / 2), 12rem);
+  grid-auto-rows: min(calc((100cqw - 42px) / var(--mobile-column-count)), 12rem);
   gap: 10px;
   padding-bottom: 10px;
 }