Still more work left with integrating apalis and need to fully update
it.
These changes are mostly for fixing the frontend I broke by eagerly
updating everything.
In the process, also improve the feedback from the import/add feed
forms.
I also replaced the frontend code to replace utc timestamps with local
time strings with @hotwired/stimulus with vanilla js.
Frontend is built with Bun. It uses Stimulus to progressively enhance
the server-built HTML. Currently, it only replaces UTC timestamps from
the server with the time in the browser's timezone.