docs(772): the merge gate decides on the COMBINED state, and skipped counts as green

Graded a nit and not blocked on, but it is a claim about a neighbouring subsystem that is
one notch too strong: the hook decides on the combined `.state` and its filters exclude
`skipped` (#593). Left as-is it would have taught the next reader that any non-success
context denies, which is what #593 exists to correct.

refs #772

docs/ci-cd.md

@@ -1652,8 +1652,9 @@ registry blip does not redden a PR — that pause is what makes failing on unkno
 shortening it silently trades this guard for flake.
 
 **It is not a `needs:` of anything, but it is not consequence-free either.** The merge-consent hook
-reads the PR's **combined** status and denies on any non-`success` context (ersatztv#598), so a red
-preflight blocks the merge exactly like any other red job. "Advisory" would be the wrong word for
+reads the PR's **combined** status and denies on a non-`success` combined state (a `skipped` context
+counts as green, ersatztv#593; an advisory red does not, ersatztv#598), so a red preflight blocks the
+merge exactly like any other red job. "Advisory" would be the wrong word for
 it — what it does not do is *skip* the jobs it diagnoses.
 
 **Recovery, without needing CI to be healthy.** The tag names a commit, and that commit still builds