`damage_curve` is what a design does at each hex out to 24, published as its own chunk (36KB gzipped) and stored a row per hex in `unit_curve`. Short, medium and long are per weapon - a small laser's long range is three hexes and a PPC's is eighteen - so there is no honest set of bands to publish and the curve is the whole answer. `hardest_between: [3, 9]` ranks what was selected by what it does across that band, hardest first: a Longbow LGB-0H tops 15-21, an Archer ARC-6W tops 3-9 under 1,600 battle value. Nobody wants damage at exactly six hexes, and every band would need a different bar to filter on. Change-Id: Ib21f2c0be747f60f7552643a0bf97aa352061c91