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/vite.config.ts

@@ -28,7 +28,11 @@ export default defineConfig({
   },
   server: {
     proxy: {
-      '/api': 'http://localhost:8000',
+      '/api': {
+        target: 'http://localhost:8000',
+        changeOrigin: true,
+        ws: true,
+      },
       '/ws': {
         target: 'ws://localhost:8000',
         ws: true,