- New api_v1/routes/admin.py: admin client management blueprint
- admin_users table for admin role (no ALTER TABLE needed)
- require_admin decorator for endpoint protection
- GET/PUT/DELETE /api/v1/admin/clients/<id>
- POST /api/v1/admin/setup (first-time admin init)
- POST /api/v1/admin/clients/<id>/suspend|activate
- GET /api/v1/admin/stats (client counts by plan)
- Registered in api_v1/__init__: auto-wired into portal_server.py
- No new service, no merge tables, no ALTER TABLE
