Section 18.3 - Deleting a key from a B-tree (legacy compatibility path)
Third-edition-numbered compatibility path for this B-tree development. The
canonical fourth-edition source is
CLRSLean.FourthEdition.Chapter_18.Section_18_3_B_Tree_Deletion;
this module forwards to it so legacy imports keep working during the
compatibility period (see docs/migrations/clrs4.md).