GeoJSON network export

Export the builder network as GeoJSON so every node and pipe carries its real-world coordinates straight into a GIS viewer, web map, or another mapping tool.

• Handing a network's geometry to a GIS team that doesn't use DekEn
• Overlaying a solved network on a web map for a stakeholder presentation
• Archiving a model's as-built geometry independent of DekEn's own format

Serializes nodes as GeoJSON Point features and pipes as LineString features, carrying id and key attributes as GeoJSON properties.