Updated shelf book management to allow scroll on mobile

Updates book drag handling to be limited to the handle so scrolling can
be done on the items themselves.
Increased handling area and improved styling to support

resources/js/components/shelf-sort.js

@@ -19,6 +19,7 @@ class ShelfSort {
             new Sortable(scrollBox, {
                 group: 'shelf-books',
                 ghostClass: 'primary-background-light',
+                handle: '.handle',
                 animation: 150,
                 onSort: this.onChange.bind(this),
             });