The routing graph from generateAllRoutes.
Spawn nodes (coloured green).
Despawn node keys (coloured red).
Optionalpositions: Map<string, [number, number]>Optional world-space positions for spatial layout.
Optionaljunction: JunctionConfigOptional junction config; when provided, nodes are grouped into labelled subgraph clusters by junction object.
A DOT-language string ready for rendering.
Converts the routing graph to a Graphviz DOT string.