Determinant routines for hex-determinant: the generic Leibniz-formula determinant for dense square matrices, the determinant behaviour of elementary row/column operations, cofactor/adjugate theory, column-tuple (Cauchy-Binet) expansion, and the two-row Plücker / Desnanot-Jacobi identities. The development is split by subject across HexDeterminant/*; this module re-exports them.