Use `America/New_York` timezone in calendar.ics instead of `UTC`

[vnprc]

Summary

Update assets/calendar.ics so that event times are expressed in US Eastern Time (America/New_York) instead of UTC. Currently all events use the Z suffix (UTC), which forces calendar apps to display times in UTC. We want to preserve the same wall-clock times and let calendar apps automatically handle Daylight Savings Time.

Details

1. Add a VTIMEZONE block to the calendar definition:

   BEGIN:VTIMEZONE
   TZID:America/New_York
   X-LIC-LOCATION:America/New_York
   BEGIN:DAYLIGHT
   TZOFFSETFROM:-0500
   TZOFFSETTO:-0400
   TZNAME:EDT
   DTSTART:19700308T020000
   RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=2SU
   END:DAYLIGHT
   BEGIN:STANDARD
   TZOFFSETFROM:-0400
   TZOFFSETTO:-0500
   TZNAME:EST
   DTSTART:19701101T020000
   RRULE:FREQ=YEARLY;BYMONTH=11;BYDAY=1SU
   END:STANDARD
   END:VTIMEZONE

   This ensures clients know the rules for Eastern Time.

2. Update event time fields to use TZID instead of Z:

   DTSTART;TZID=America/New_York:{{ event.start | date: "%Y%m%dT%H%M%S" }}
   DTEND;TZID=America/New_York:{{ event.end | date: "%Y%m%dT%H%M%S" }}

   Remove the trailing Z, and add TZID=America/New_York.

3. Testing

   • Rebuild the site and download calendar.ics.
   • Import into Google Calendar, Apple Calendar, and Outlook.
   • Verify October events show EDT (UTC-4) and December events show EST (UTC-5) at the same local clock times.

Acceptance Criteria

• All events display at the same local time as entered in the Jekyll front matter.
• Calendar apps automatically handle DST shifts.
• No UTC (Z) timestamps remain in the file.