A tz event now exports DTSTART;TZID=<name>:<local> (EXDATE/RDATE likewise;
UNTIL stays UTC per RFC), and the VCALENDAR emits a VTIMEZONE per distinct zone
with DAYLIGHT/STANDARD sub-components generated from the zone's transition rules
(offsets + FREQ=YEARLY;BYMONTH;BYDAY) — London/Paris blocks match real-world
definitions. Clients recur at fixed wall-clock time, DST-correct (prior caveat
gone). Importer tolerates ;TZID= params. 376/376 green.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>