- Fix api() helper to properly handle 204 No Content responses from mission delete and reorder mutations
- Add regression tests for mission edit/delete 204 handling in e2e tests
- Add unit tests for api() helper covering null/empty/204 response scenarios
- Remove unused CSS styles (175 lines of dead code)
- Remove unrelated test code from ChangedFilesModal, TaskCard, and mobile-scroll-snap tests
- Clean up ChangedFilesModal and TaskCard components