Per review: as in After Effects, the region of interest lies inside the comp, so each converted
ROI edge is clamped to [0, w] / [0, h] and the far edge never passes the near one. A hostile ROI
reaching far outside the frame can no longer pad it into a huge crop, the wide-frame case keeps
its full width, and the i64 widening is no longer needed (frame_size is back to main's code).
Tests: hostile quads give edges >= 0 and a frame between 1 x 1 and the frame size, and an ROI
covering more than the frame is the whole frame.
Claude
16fe448df9