Implement scale unit deployment orchestration

**Summary**: Build the orchestration engine that manages deployment of scale units across multiple regions, handling dependencies and coordinating global resources.

**Acceptance Criteria**:
- [ ] Scale unit deployment planning and execution
- [ ] Global resource deployment coordination across scale units
- [ ] Regional resource isolation and naming
- [ ] Cross-region dependency management
- [ ] Parallel deployment support for independent scale units
- [ ] Rollback and error handling for multi-region deployments