Refactored calendarfetcherutils to remove as many of the date conversions as possible and use moment tz when calculating recurring events, this will make debugging a lot easier and fixes problems from the past with offsets and DST not being handled properly. Also added some tests to test the behavior of the refactored methodes to make sure the correct event dates are returned

Author: plebcity

CHANGELOG.md

@@ -34,6 +34,10 @@ planned for 2025-07-01
 - [refactor] Replace `ansis` with built-in function `util.styleText` (#3793)
 - [core] Integrate stuff from `vendor` and `fonts` folders into main `package.json`, simplifies install and maintaining dependencies (#3795)
 - [l10n] Complete translations (with the help of translation tools) (#3794)
+- [refactor] Refactored `calendarfetcherutils` in Calendar module to handle timezones better
+  - Removed as many of the date conversions as possible
+  - Use `moment-timezone` when calculating recurring events, this will fix problems from the past with offsets and DST not being handled properly
+  - Added some tests to test the behavior of the refactored methodes to make sure the correct event dates are returned
 
 ### Fixed