Backend: activate endpoint returns 409 with structured warning when
start_date is in the future; accepts force=true to bypass.
test_crud_service: always excludes tests from draft campaigns with future
start_date so they do not appear in the team queue prematurely.
Frontend: catches 409 on activate and shows amber confirmation modal
with Keep scheduled / Activate now anyway options.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>