Add superuser admin interface for managing organizations and users:
- Admin layout with access control (redirects non-superusers)
- Admin dashboard with org/user counts and quick actions
- Org management: list, create, view/edit details, manage sites
- User management: list, view details, toggle superuser, confirm email
- SuperuserBadge component for consistent superuser indication
- Sidebar shows admin link (shield icon) for superusers only
- Centralized date formatting utility at $lib/utils/format-date.ts
- Test plan documentation at docs/test-plans/admin.md
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
Add organization management UI pages:
- /dashboard: Org list with grid cards
- /dashboard/[slug]: Org overview with stats and previews
- /dashboard/[slug]/members: Member management with invites
- /dashboard/[slug]/settings: Org settings, leave, delete
- /invite/accept: Token-based invite acceptance flow
Includes shared org context layout for role detection, reusable
components (role-badge, confirm-dialog), and sidebar nav update.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
