Intl.DateTimeFormat timeZone option or manual offset math for zone-correct display?
A scheduling dashboard stores every timestamp in UTC but must render each one in a per-user IANA zone such as America/New_York or Asia/Tokyo, without mutating the stored instant. Two documented paths Intl.DateTimeFormat (ECMA-402) takes a timeZone option: it formats an existing Date in a named zone and leaves the underlying epoch untouched. The alternative i