- Rename collabs/ directory to labs/
- Rename workflow files: collabs-publish-*.yml → labs-publish-*.yml
- Update all paths in workflows, Quarto configs, and navbars
- Update cross-references in book, kits, and dev-landing
- Update site-url to mlsysbook.ai/labs/
Note: GitHub repo variable DEV_COLLABS_PATH needs to be renamed
to DEV_LABS_PATH in repository settings.
Absolute paths like /book/ resolve incorrectly on GitHub Pages subpath
deployments (cs249r_book_dev). Using relative paths (./book/) ensures
the links work regardless of the hosting location.