DotGraphGenerator

Renders a ModuleDependencyGraph as a Graphviz digraph definition (DOT).

DOT is the lingua franca of graph tooling: dot -Tsvg, dot -Tpng, Gephi, and countless viewers consume it. Like the Mermaid export it is plain text and deterministic - nodes are emitted in sorted path order so the same graph always produces byte-identical output that diffs cleanly in review.

Output shape:

• digraph with one box node per module, filled with its module-type colour.

• Production edges are solid; test-only edges are dashed.

• Parallel edges between the same pair collapse into one link (solid wins over dashed).