Converts wall-clock times from a source IANA time zone to several target zones, with UTC offsets, weekdays and day-shift markers (+1 day). Accepts YYYY-MM-DD HH:MM[:SS], HH:MM (today in the source zone), ISO strings with an explicit offset (the source zone is then ignored), and now; leave the input empty for a world clock. Daylight-saving rules come from the browser's time-zone database; a time inside a spring-forward gap moves forward to the next valid time. Everything runs locally.