Add comprehensive clients management interface including:
- Client table with search, filtering, and pagination
- Client form for creating and editing clients
- Client detail dialog showing profile, membership, and stats
- API endpoint for individual client operations (GET, PUT, DELETE)
- Stats cards showing total clients, with membership, and new this month
- Integration with membership assignment dialog
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
