pl-fe: make tombstones focusable

Signed-off-by: marcin mikołajczak <git@mkljczk.pl>

packages/pl-fe/src/components/tombstone.tsx

@@ -22,6 +22,7 @@ const Tombstone: React.FC<ITombstone> = ({ id, onMoveUp, onMoveDown }) => {
       <div className='h-16'>
         <div
           className='focusable flex h-[42px] items-center justify-center rounded-lg border-2 border-gray-200 text-center dark:border-gray-800'
+          tabIndex={0}
         >
           <Text theme='muted'>
             <FormattedMessage