- Lift AppNav from CalendarShell to App.tsx as a sibling of <Routes>
- App.tsx fetches /api/me (same query key as CalendarShell — deduplicated by TanStack Query)
- App.tsx provides the outer layout (phone: column, desktop: row) with AppNav always rendered
- CalendarShell simplified: no longer manages AppNav, outer flex layout stays in App.tsx
- AuthSplash gains overlay prop (position:fixed inset:0 z-index:999) so it covers AppNav when needed
- CalendarShell uses AuthSplash with overlay=true so auth splashes cover full viewport
- Remove onOpenSettings prop from CalendarShell (wired directly in App.tsx to SettingsSheet)
- Desktop sidebar nav (FamilySync brand, Calendar/Lists links) now persists on /lists route