paper2video - paper/assets/deck -> narrated MP4

paper2video is an orchestrator. It does not try to replace poster extraction, deck authoring, TTS, or ffmpeg compositing. It wires the current best pieces together:

paper.pdf
  -> skills/paper2assets/scripts/build_package.py
  -> assets/meta/sections.json + assets/meta/narration.json
  -> deck source (ppt-master / paper2slides / existing PPTX)
  -> assets/audio/*.mp3 from skills/paper2poster/scripts/generate_audio.py
  -> raw MP4 from skills/paper2video/scripts/render_video.py
  -> timeline.json from skills/paper2video/scripts/build_timeline.py
  -> video.mp4 with burned-in subtitles from add_subtitles.py