Numismatics' x8 uniform chain isn't intuitive. Mod values are
hardcoded so we cant fix the ratios, but we can put the conversion
table directly on each coins tooltip via KubeJS ItemEvents.tooltip.
Players hover any coin -> see how it relates to the others + a hint
to use Bank Teller for on-the-fly conversion.
~25 lines, ItemEvents.tooltip hot path is cached per item-id so no
performance concern.
