Slides were not loading on the live site because the PDFs exist in a
GitHub Release (tinytorch-slides-v0.1.0) but were never downloaded
during the build process. The .gitignore has *.pdf which prevents
slides from being committed to git.
Add a step to both deployment workflows to download all slide PDFs
from the release and inject them into _static/slides/ before deploy.
Fixesharvard-edge/cs249r_book#1162