.add() does not take the given time zone and uses local system time zone resulting in incorrect date times during daylight savings

[hannahbrown97]

Describe the bug
In UTC the datetime string 2025-03-08T15:30:00+00:00 converted to time zone Australian/Adelanie 2025-03-09T03:00:00+10:30. which is wrong, it should be 02:00. The dayjs object has raw data using my local system time CST, the time zone and offset are set to Australian/Adelanie but since my local time is observing DST , it incorrectly converts.

This occurred when trying to create a list of times and adding a given interval
dayjsObj.add(15, 'minute')
it would be correct in UTC but if the dayjsObj was given another time zone while my local system was CST it would go from 2025-03-09T01:45:00+10:30 to 2025-03-09T03:00:00+10:30 which is incorrect

Expected behavior
when adding toa dayjs oobject with dayjsObj.add(15, 'minute') given the time zone +10:30 it should go from 2025-03-09T01:45:00+10:30 to 2025-03-09T02:00:00+10:30

Information

• Day.js Version [e.g. v1.0.0]
• OS: [e.g. iOS]
• Browser [e.g. chrome 62]
• Time zone: [e.g. GMT-06:00 DST (CST)]