feat: lasso selection, multi-select panel, and named groups

- Add lasso/box selection via selectionOnDrag (Space to pan, lasso by default)
- Add lasso/pan toggle button in canvas controls (bottom-left)
- Multi-select panel in right panel when 2+ nodes selected (including zones)
- Create named Group node from selected nodes with bounding box math
- Group node: resizable, inline rename, show/hide border toggle, status summary
- GroupDetailPanel: lists members, online/offline count, ungroup action
- Fix group persistence after save/reload (extend proxmox container map to include group nodes)
- Fix groupRect serialization to preserve parent_id
- Remove background color from group and proxmox container node wrappers
- Add tests for all new store actions, GroupNode, MultiSelectPanel, GroupDetailPanel

frontend/src/types/index.ts

@@ -16,6 +16,7 @@ export type NodeType =
   | 'docker'
   | 'generic'
   | 'groupRect'
+  | 'group'
 
 export type TextPosition =
   | 'top-left'
@@ -76,6 +77,7 @@ export interface NodeData extends Record<string, unknown> {
     label_position?: 'inside' | 'outside'
     text_size?: number
     z_order?: number
+    show_border?: boolean
     width?: number
     height?: number
   }
@@ -112,6 +114,7 @@ export const NODE_TYPE_LABELS: Record<NodeType, string> = {
   docker: 'Docker Host',
   generic: 'Generic Device',
   groupRect: 'Group Rectangle',
+  group: 'Node Group',
 }
 
 export const STATUS_COLORS: Record<NodeStatus, string> = {