- Implement PostgresUserRepository with full CRUD operations
- Support all query methods (by_id/email/username/token)
- Use psycopg2 with RealDictCursor for clean mapping
- Create initial schema migration (users/workspaces/members/invitations)
- Add database indexes for performance
- Setup foreign key constraints for data integrity
- Include migration guide and rollback instructions
- Add psycopg2 dependency
Phase 4 Task 28/68 completed