💄(frontend) fix flickering tree title

The title was flickering because the icons were
loading and pushing the div to the left. We do not
need the icons part if we are not hovering the tree
item, so we can hide it until we hover the item.

src/frontend/apps/impress/src/features/docs/doc-tree/components/DocTree.tsx

@@ -305,8 +305,8 @@ export const DocTree = ({ currentDoc }: DocTreeProps) => {
             }
 
             .doc-tree-root-item-actions {
-              display: flex;
               opacity: ${rootActionsOpen ? '1' : '0'};
+              display: ${rootActionsOpen ? 'flex' : 'none'};
 
               &:has(.isOpen) {
                 opacity: 1;