Extract Authenticity Evidence from Procreate Canvas

Step 2.1 of the pipeline extracts authenticity evidence: - Artist signature PNG (visual authenticity marker) - Timelapse video segments (forensic creation evidence)

The `.comp_*()` functions perform local extraction only. The `.upload_*()` functions handle CDN uploads.

Details

Pure computation functions for extracting signature and video segment evidence from Procreate canvas files. These are the building blocks for [extract_signature()] and [extract_video_segments()].

See also

Other extraction functions: extract_creation_window(), pl-extract-createdate, pl-extract-meta, pl-extract-signature, pl-extract-stats, pl-extract-timelapse, pl-extract-videos