TreeNode.svelte:
- Native HTML5 drag-and-drop with move effect
- Lazy tree expand/collapse (arrow for container types only)
- Drop validation: no self-drop, container-only, descendant check
- 'case' icon kind added
App.svelte:
- toggleExpand loads children via ListChildren into tree
- handleNodeDrop calls MoveNode(draggedId, targetId), refreshes tree
- Root workspace area is a drop target (handleDropRoot)
- Overview section shows nodeKindLabel instead of raw type enum
- Context menu shows Create only for container types
- Create modal title uses 'Создать элемент'
- submitCreateNode expands parent after child creation
TemplateIcon.svelte: added 'case' icon (folder-like with dividers)
i18n: added nav.createNode key (ru+en)
mirivlad