feat: implement Markdown and HTML page imports (#85)

* page import feature
* make file interceptor common

* replace @tiptap/html
* update tiptap version

* reduce table margin

* update tiptap version

* switch to upstream drag handle lib (fixes table dragging)

* WIP

* Page import module and other fixes

* working page imports

* extract page title from h1 heading

* finalize page imports

* cleanup unused imports

* add menu arrow

apps/client/src/features/page/components/header/page-header-menu.tsx

@@ -60,7 +60,7 @@ function PageActionMenu({ readOnly }: PageActionMenuProps) {
   });
   const { openDeleteModal } = useDeletePageModal();
   const [tree] = useAtom(treeApiAtom);
-  const [opened, { open: openExportModal, close: closeExportModal }] =
+  const [exportOpened, { open: openExportModal, close: closeExportModal }] =
     useDisclosure(false);
 
   const handleCopyLink = () => {
@@ -156,7 +156,7 @@ function PageActionMenu({ readOnly }: PageActionMenuProps) {
 
       <PageExportModal
         pageId={page.id}
-        open={opened}
+        open={exportOpened}
         onClose={closeExportModal}
       />
     </>