Builds the graphify knowledge graph after each semantic-release and attaches it
to that release as knowledge-graph-v<version>.tar.gz, so every developer can fetch
the map for a given version. The map carries its own identity — released package
versions, tag and commit — in build_meta.json and embedded in graph.json, which is
what lets a consumer tell a current map from a stale one. The graph is never
committed; graphify-out/ is gitignored.
