0.2.42 native DBS persistence
- Restores saved Drive-By-Sable graph state through CableNetworkManager.mergeSavedConnections.
- Native DBS -> DBS schematic connections remain first-class saved cable data.
- Legacy DBW/Photomancy connections migrate into DBS through the same saved-network merge path.
- Avoids transient createConnection validation during schematic placement.
- Rejects ghost/air endpoints instead of creating stale graph entries.
