Section 23.2 - Incremental costed Kruskal (legacy compatibility path)
Third-edition-numbered compatibility path for incremental costed Kruskal. The canonical
fourth-edition source is
CLRSLean.FourthEdition.Chapter_21.Section_21_2_Kruskal_And_Prim.S2_StatefulKruskal;
this module forwards to it so legacy imports keep working during the
compatibility period (see docs/migrations/clrs4.md).