Archive-grounded colour harmonies in LCh perceptual colour space.

For each harmony type, rotates the input hue in LCh space, then finds the nearest named archive colour to each harmony target using CIEDE2000.

Returns named archive colours as harmonic partners -- with provenance, cultural context, and source -- not just hex codes.

"hay_contrast" is a different kind of harmony type from the rest: not a fixed-angle rotation, but D.R. Hay's (1838) documented contrast pairing between six named hues, snapped from the input's nearest hue rather than rotated from it, and returning Field's proportional power for the pair (attributed to Field, not Hay, throughout) alongside the CIEDE2000 archive match. Declines to answer (covered: false) rather than guess for a hue nearer a tertiary region than any of the six -- Hay's data has no specific number for those.

Example: {"hex": "#1B1556"}

Returns complementary, analogous, triadic, and split-complementary archive colours for Iago Venom (Shakespeare, Othello II.3.347).