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