- load() fetches /api/groups in parallel with /api/invites; returns
sorted groups array and groupsLoadError for partial failures
- create action forwards groupIds[] to POST /api/invites so invited
users are placed in the selected groups on registration
- +page.svelte: group checkboxes via UserGroupsSection inside the form;
amber warning banner when groups could not be loaded
- page.svelte.test.ts: groups checkboxes + warning banner tests
- page.server.test.ts: parallel fetch, sorting, error fallback,
groupIds in POST body
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>