Section 25.3 - Johnson's algorithm for sparse graphs (legacy compatibility path)
Third-edition-numbered compatibility path for Johnson's algorithm. The canonical
fourth-edition source is
CLRSLean.FourthEdition.Chapter_23.Section_23_3_Johnsons_Algorithm;
this module forwards to it so legacy imports keep working during the
compatibility period (see docs/migrations/clrs4.md).
Declarations retain the CLRS.Chapter24.WeightedGraph namespace.