Revisit dashboard timezone fix for east-of-Mountain brands

Investigate the dashboard timezone bug where day-based metrics are one day off for brands ahead of Mountain Time, and capture the performance regression that caused previous fixes to be rolled back.

Transcript Context

The team discussed that "booking today" and similar dashboard metrics are off for brands east of Mountain Time, with TLC called out as an example but the issue affecting all eastern brands. Chris said a previous fix had been implemented more than once, but each attempt caused major performance issues or destabilized the app the next day, so the change had to be removed.

This follow-up should capture both sides of the problem: the user-facing date bug and the regression/performance risk introduced by the prior fixes. The transcript also suggests this may have fallen off the active list after rollback and should be re-added with that context.