Read-only Package Preview Prototype
This is the first authoring-system vertical slice. It reads a Scrivener project, checks the project structure, and builds an on-screen package preview. It does not call a model and it does not write to Scrivener.
Run from Authoring_System:
python3 prototype/app.py
Then open http://127.0.0.1:8765.
To point it at another project:
python3 prototype/app.py --project /absolute/path/to/Book.scriv
The app binds scene/brief pairs by the visible Scene X labels for this read-only prototype. The next phase will persist UUID bindings in a sidecar, so later renaming does not break relationships.