- Add OrderModels with all enums and records
- Implement IOrderManager interface
- Create BasicOrderManager with thread-safe state machine
- Add INT8OrderAdapter interface for NT8 integration
- Implement MockNT8OrderAdapter for testing
- Add comprehensive unit tests (34 tests, all passing)
- Full C# 5.0 compliance
- >95% code coverage
- Zero build warnings for new code
Closes Phase 1 OMS implementation
