:sparkles: Standardize Dates Across The Compass API

[victor-enogwe]

Feature Description

We need to ensure that all dates are stored in UTC, that we respect timezones when doing date conversions whenever they are available, and ensure that the date conversions work cross-environment and cross-platform.

Use Case

This will ensure that the calendar events date and times are accurately calculated and presented. It will also allow us to enable custom recurring events edit, allowing us to update time series correctly.

Additional Context

Needed before #378 - #383

[tyler-dane]

and ensure that the date conversions work cross-environment and cross-platform

We do not need to do this anytime soon, per the Anti-Priorities in the 2025 Roadmap. https://docs.compasscalendar.com/docs/roadmap#anti-priorities

Let's keep this issue as focused as possible. Our main focus on the backend should be finishing the recurring event feature. I know doing this will help do that. But please be careful to not go overboard with the refactors just yet.

@victor-enogwe

[victor-enogwe]

Hi @tyler-dane I totally agree, all the stories won't be done now, just the ones important enough to help us with the sanity check on dates.

For example #609 - #610 will not make the cut until the subcalendars are done.

[tyler-dane]

@victor-enogwe OK cool. I changed the milestone and removed the dates from this parent issue in order to make this distinction more clear from the timeline view. Let's continue to track the dates/milestone in the children issue

[tyler-dane]

Moved milestone back so we can focus on profitability through December