Copied unchanged from the bridge kit (727fb55): TUTORIAL.md (for the repository's GitHub admin,
about 10 minutes), pull-contributor.yml (the workflow it sets up; it refuses a contributor's
changes to .github/) and test-pull-contributor.sh (the TUTORIAL's "check the guard yourself",
which sits next to it). None of them is under .github/, so nothing runs by itself here.
README: one line in the agent section links the tutorial; nothing else in README changes.
