Add an answer or completed uploads

Files must be completed uploads owned by the member. For external screen recordings, transfer the complete original with upload_my_file and complete_my_file first, then set files[].recordingMode to screen here. recordingMode accepts screen or camera, defaulting to camera. Toma validates processed content independently of the declaration. The five-minute clip and 100 MiB file limits remain. Prepared explicit task recordings become public only after approval; original uploads and answers remain private. unavailable requires an explanation and reassessment rather than automatically waiving a consequential gap. New sessions begin assessment only after analyze. A fresh handoff is unnecessary when existing Context is sufficient.