fix(group): preserve children + size on edit, fix status WS proxy

- Skip NodeModal on double-click for 'group'/'groupRect' (use inline rename)
- Exempt 'group' from properties-clears-height rule in updateNode
  (was collapsing group + hiding children with extent: 'parent')
- Enable ws: true on Vite /api proxy so /api/v1/status/ws/status upgrades
  (status bubbles stayed grey because WS handshake failed)
- Add regression tests for group/groupRect height preservation

frontend/src/App.tsx

@@ -465,6 +465,11 @@ export default function App() {
   }, [])
 
   const handleNodeDoubleClick = useCallback((node: Node<NodeData>) => {
+    // 'group' uses inline rename (pencil button in header). Opening the
+    // generic NodeModal would clobber the group's height (via the
+    // properties-clears-height rule in updateNode) and lose its children.
+    // 'groupRect' has its own onDoubleClick that already routes to GroupRectModal.
+    if (node.data.type === 'group' || node.data.type === 'groupRect') return
     handleEditNode(node.id)
   }, [handleEditNode])