//! Modules implementing individual curve families.
/// Gray-code based traversal over a hyper-rectangular grid.
/// Hairy Onion: tiled 2D onion spirals connected in higher dimensions.
/// H-curve: a Hilbert-like family using BRGC and orientation transforms.
/// Classic Hilbert curves and utilities.
/// Internal 2D Hilbert helpers.
/// Shared helpers for Hilbert variants.
/// Internal N-D Hilbert helpers.
/// Onion curve family operating on L∞ shells (single consolidated module).
/// Simple serpentine scan (boustrophedon) traversal.
/// Z-order (Morton) bit-interleaving.