- Backend: add HasChildren field to NodeDTO; ListWorkspaceTree/ListChildren
populate it by querying CountChildren for container types
- Node repository: add CountChildren(parentID, types...) method
- TreeNode: toggle shown only when has_children (not isContainer); double-click
on row = expand/collapse; icon click = expand/collapse; drop-valid class via
DOM classList for DnD highlight; auto-expand collapsed container on 500ms
hover during drag; auto-scroll near edge during drag
- App.svelte: selectNode no longer resets workspaceTree/expanded; new
reloadTreePreservingExpanded() helper re-fetches children for all expanded
nodes after DnD move / delete; deleteWorkspaceNode preserves expanded state
mirivlad