Adds a new "+ New collective" entry at the bottom of the sidebar
collective-switcher dropdown (and the mobile drawer for parity).
Clicking it opens a CreateCollectiveModal that reuses the same
onboarding form — name + emoji grid — and calls the existing
create_collective() RPC (migration 012). On success, the new
collective is appended to $userCollectives, set active in
$currentCollective, persisted to localStorage, and the user is sent
to /lists.
Side effects:
- Switcher now opens even with a single collective (previously gated
on >1) so the entry is always reachable; the chevron is always
shown.
- DesktopSidebar gets a data-testid on the switcher button so the
Playwright suite can target it without text matching.
O-04 (rescued from Fase 7): Eva creates her first collective via
onboarding, then opens the switcher and creates a second one without
leaving /lists; both collectives end up in the switcher and the DB.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
