- main.py: 4 helper funcs (_persist_to_s3, _ensure_local, _delete_from_s3,
_ffmpeg_then_persist) - no-op fallback when S3 creds missing
- save_job(): mirror metadata JSON to S3
- process_job(): mirror YT download + render output + analysis/srt/ass to S3
- upload_video(): mirror direct uploads to S3
- _precache_edit_assets(): Popen->threaded with S3 sync after ffmpeg
- read endpoints (download, preview, source_video, waveform, preview_clip,
get_transcript, recut_job): _ensure_local() fallback fetch from S3
- delete_job(): cascade delete to S3 (mirror unlink)
- cleanup.py: NEW module, deletes local files >48h that exist in S3.
Verified by S3 head_object + size match. NOT YET ACTIVATED in cron.
Backward compat: lokalna mapa ostane primary. Brez env vars S3_* vsi
helperji vrnejo False (no-op). Production behavior identičen, dokler
ne dobi S3 creds.
