Export improvements (#22867)

* backend

* frontend + i18n

* tests + api spec

* tweak backend to use Job infrastructure for exports

* frontend tweaks and Job infrastructure

* tests

* tweaks

- add ability to remove from case
- change location of counts in case card

* add stale export reaper on startup

* fix toaster close button color

* improve add dialog

* formatting

* hide max_concurrent from camera config export settings

* remove border

* refactor batch endpoint for multiple review items

* frontend

* tests and fastapi spec

* fix deletion of in-progress exports in a case

* tweaks

- hide cases when filtering cameras that have no exports from those cameras
- remove description from case card
- use textarea instead of input for case description in add new case dialog

* add auth exceptions for exports

* add e2e test for deleting cases with exports

* refactor delete and case endpoints

allow bulk deleting and reassigning

* frontend

- bulk selection like Review
- gate admin-only actions
- consolidate dialogs
- spacing/padding tweaks

* i18n and tests

* update openapi spec

* tweaks

- add None to case selection list
- allow new case creation from single cam export dialog

* fix codeql

* fix i18n

* remove unused

* fix frontend tests