- Implement DependencyContainer for all repositories and use cases
- Create singleton pattern for repository instances
- Factory methods for all use cases (auth + workspace)
- Auth middleware: get_current_user with JWT verification
- Permission middleware: require_workspace_access/admin/owner
- Support optional authentication (get_current_user_optional)
- Integrate with PermissionChecker and QuotaChecker
Phase 4 Task 25/68 completed