Bulk Room Reservations gives Unix Epoch date (12-31-1969) for conflicting with dates the library is closed vs. actual dates.

Problem/Motivation

When attempting to make bulk room reservations if some of the reservations fall on a date where the library is closed instead of saying the dates that it fails on Intercept says Example Room is closed on 12-31-1969

Steps to reproduce

Setup Intercept with the demo_profile_content module enabled and attempt to schedule a repeating event that is weekly for Monday through Friday - select East Branch and it will display
East Study Room 1 is closed on 12-31-1969
East Study Room 2 is closed on 12-31-1969
East Study Room 3 is closed on 12-31-1969

Proposed resolution

It should display the appropriate dates that the library is closed & maybe not make reservations for dates the library isn't open. Currently it appears to make the reservations anyways.

Remaining tasks

A Merge Request has been opened - this code has been assisted by AI but validated and tested by myself

User interface changes

It will show the appropriate date for conflicts in the warning message

API changes

Data model changes