Build real PNG, WAV, and MP4 fixtures (no AI models) and exercise the
full assembler and Creative Director pipeline end-to-end. Fix MoviePy v2
crossfade API (vfx.CrossFadeIn) and font resolution (DejaVu-Sans).
14 new integration tests — 638 total, all passing.
https://claude.ai/code/session_01KJm6jQkNi3aA3yoQJn636c
