ci: state where the nightly race and fuzz sweeps run

Assisted-by: GLM 5.3

.gitea/workflows/test.yml

@@ -1,8 +1,9 @@
 # Test, Go. Push and pull request to development. Never on main.
 #
 # The gates are the ones the justfile's `gates` recipe runs, minus race: the shared
-# runner box cannot afford the race detector on every push, so race runs once inside
-# the release pipeline instead. The box is one core and 2 GB beside Gitea, so
+# runner box cannot afford the race detector on every push. Race has its own
+# pipeline, dispatched by hand and swept nightly, and the local `just gates`
+# runs it once per task. The box is one core and 2 GB beside Gitea, so
 # parallelism is bounded on purpose and everything runs in one job. Extra jobs would
 # duplicate the checkout, the Go setup and the dependency download three times without
 # buying any parallelism.