Issue #12: on installs with no ffmpeg on PATH (Windows portable), Shot Join's
mp4 mode - also picked automatically for long videos when the RAM is short -
failed with WinError 2. Video files now go through bfs_video_io: ffmpeg from
PATH, else imageio-ffmpeg's, else PyAV (what ComfyUI's Save Video uses), for
writing and for reading the MP4 back. BFS Video Compare uses the same writer.
Issue #13: a workflow saved with Max shots = 1 silently dropped every shot
after the first, so double-click splits did nothing. A split made by hand now
raises Max shots to keep it, and the Video tab says when detected shots are
left out by the limit.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
