Move canvases and attachments between workspaces

Export with images and files saves the canvas and accessible attachments in one bundle. Import it into an empty workspace to create a separate copy. Selected blocks and groups can be copied between workspaces together with their attachments.

Copy as image places a single image or a composition of several blocks on the system clipboard as a PNG. This requires browser permission. Download originals individually or as a ZIP archive; original filenames are preserved when their metadata is available.

Attachment access checks and filename handling during import and download have been strengthened. Export and copying respect workspace access and restrictions on hidden canvas elements.