18.2. Direct integer coordinates
Let f have leading coefficient c. The finite-field target is the
monic unit multiple c⁻¹ f mod p.
Hex.ZPoly.monicTarget is its canonical integer lift modulo
p^a. This multiplication by a unit in 𝔽_p does not change the
integer variable or apply a coefficient-swelling substitution.
During recombination, scaling a selected lifted product by c
returns it to the coordinates of f. Centred coefficient recovery,
primitive-part extraction, and sign normalization then give a factor
of the original polynomial.
Classical and lattice recombination use the same modular factorization, factor indices, and direct-coordinate Hensel lift.