The job was named "test", colliding with core CI's "test" matrix so the PR
checks list showed two "test (3.11)" rows. Rename it to "understone" so the
example's checks read unambiguously (understone (3.11) / (3.13)).
The door-game example is a standalone package (no turnstone-core
dependency) that the root suite does not collect — its
testpaths are scoped to ["tests"], so the example's 419 tests, ruff,
and mypy gates never ran in CI.
Add a path-filtered workflow that installs the example and runs its
full gate (pytest + ruff check + ruff format --check + mypy) whenever
examples/door-game (or this workflow) changes, across the example's
declared Python floor and ceiling (3.11, 3.13). Pinned action SHAs and
contents:read permissions match the existing CI workflows.