Enhancement: Native timezone support for recurring events

[naringst]

I'm currently implementing recurring events with RRule and need to handle timezone-specific repetitions. Currently, when setting a recurring event for 11:32 AM KST with tzid: 'Asia/Seoul', RRule doesn't automatically generate recurrences in Korean local time. Instead, I have to manually adjust the times by calculating UTC offsets.

Current workaround:

// Creating RRule with local time
const koreanEvent = new RRule({
 dtstart: datetime(
   localDate.getFullYear(),
   localDate.getMonth() + 1,
   localDate.getDate(), 
   11, // 11:32 KST
   32,
 ),
 tzid: 'Asia/Seoul',
 ...options
});

// Processing results
const dates = koreanEvent.all().map(utcDate => {
 return moment.tz(utcDate, 'Asia/Seoul')
   .subtract(utcOffset, 'hours')
   .toDate();
});

Feature request: Could RRule natively handle timezone-aware recurrences? For example, if I set:

new RRule({
  dtstart: someDateTime,
  tzid: 'Asia/Seoul',
  ...otherOptions
})

It would be helpful if RRule could directly return dates in the specified timezone without manual offset calculations.
Please let me know if I'm misunderstanding any part of RRule's timezone functionality. Thank you for considering this request!

[joao-moonward]

I also need this feature; I can try to spend some time on it.
This is where I reckon we can start the implementation.

rrule/src/optionstostring.ts

Line 15 in 9f2061f

if (keys[i] === 'tzid') continue

I wish the maintainer were active in this project, but if I create a PR, it will never get approved