Usage detail for one event name

One event name's totals: how many times it fired, how many distinct contacts triggered it, and when it was first and last seen.

contactCount counts only events that were attributed to a contact — events tracked without a resolvable address raise count without raising it, so the two legitimately disagree.

An unknown name answers 200 with zeros rather than 404, so this endpoint cannot tell you "never fired" from "you misspelled it". When a trigger looks dead, check GET /v1/events/names for what you are actually sending.

Takes the same optional window as GET /v1/events/stats, so drilling from a ranged list into one name keeps the range and the two agree. With no range this covers all time, as it always has.