Selectively revert changes after April 10, 2024

[eradman]

In #6876 I proposed a change to revert all commits >= 3f19534 to bring the project back to a stable condition.

Since changes were made to the frontend, server, CI, and build, tests will not pass when rolling back everything. @justinclift asked if we could stage these changes: trying to roll back to a stable condition in a strategic manner seems wise, so my plan of record is to:

1. Revert CI
2. Revert Build
3. Extensively test Rash manually
   a) fix any bugs found
   b) selectively roll back changes to the server and/or UI
4. Reinstate features that were inadvertently removed in steps 1-3

I will post each pull request in this thread.

[eradman]

Pull requests for step 1 and 2:
#6965
#6967

[eradman]

Pull request for step 3(b)
#6969

[eradman]

Another pull request for step 3(b)
#6971