Implements the remaining zone slave management endpoints from the official
Bose SoundTouch Web API v1.0 specification, bringing API coverage to 89%.
## New Features
### Client Methods
- AddZoneSlave(masterID, slaveID, slaveIP) - Add individual device to zone
- AddZoneSlaveByDeviceID(masterID, slaveID) - Add device by ID only
- RemoveZoneSlave(masterID, slaveID, slaveIP) - Remove individual device
- RemoveZoneSlaveByDeviceID(masterID, slaveID) - Remove device by ID only
### Models
- ZoneSlaveRequest - Request structure for slave operations
- ZoneSlaveEntry - Individual slave entry with IP address support
- Complete XML marshaling/unmarshaling with proper omitempty handling
- Comprehensive validation and error handling
### CLI Commands
- zone add-slave --master ID --slave ID [--slave-ip IP]
- zone remove-slave --master ID --slave ID [--slave-ip IP]
## Implementation Details
- Follows official API specification exactly (POST /addZoneSlave, /removeZoneSlave)
- Supports both device ID + IP and device ID only operations
- Comprehensive input validation (IP addresses, device ID conflicts)
- Proper XML formatting with omitempty for optional IP addresses
- Extensive test coverage (580+ lines of tests)
- Integration with existing high-level zone management API
## Testing
- 200+ new test cases covering all functionality
- Complete model validation and XML marshaling tests
- HTTP client integration tests with mock servers
- Error handling and edge case coverage
- Network error simulation tests
## Documentation Updates
- Updated API coverage from 84% to 89% (17/19 endpoints)
- Comprehensive API coverage analysis document
- Updated README.md with new endpoint status
- Added practical usage examples
- CLI help documentation
## Compatibility
- Maintains full backward compatibility
- Complements existing high-level zone API
- Users can choose between low-level official API or enhanced high-level API
- No breaking changes to existing functionality
This implementation provides both the exact official API endpoints and
enhanced high-level zone management, giving users maximum flexibility
for zone operations while maintaining full API compliance.
