By: Tom Sydney Kerckhove <syd@cs-syd.eu>
ical-recurrence: add unresolveTimestampR to render a Timestamp in a display timezone resolveDateTime turns a UTC/zoned DateTime into an absolute TimestampUTCTime. Consumers that want to show that instant as a human-readable local time must convert it back into a display timezone's wall-clock -- and doing that by hand (keeping the UTC wall-clock) is wrong by the zone's offset (1-2h). This adds the DST-correct helper so consumers stop hand-rolling it. Regression test encodes the concrete case that was mis-handled downstream: a 19:00Z instant in a +02:00 (CEST) zone renders as 21:00 local, not 19:00.