Section 26.2 - Shortest augmenting paths (legacy compatibility path)

Third-edition-numbered compatibility path for shortest augmenting paths. The canonical fourth-edition source is CLRSLean.FourthEdition.Chapter_24.Section_24_2_Edmonds_Karp.S1_ShortestAugmentingPath; this module forwards to it so legacy imports keep working during the compatibility period (see docs/migrations/clrs4.md).