cctest: unify merge policy wording — recipe PRs are never agent-merged, both sides

Operator decision: no policy difference between cc-ci and recipe-maintainer. On
inspection ARM already agrees (recipe-upgrade-cron-all: 'PRs are reviewed and merged
manually by a human afterwards... never merges anything'; 'no human review in the
middle' = skip the mid-run plan confirmation only). Wrappers previously framed this
as a cc-ci override over ARM auto-merge flows — wrong reading; now stated as ONE
unified rule. /help conventions updated to match.

.opencode/skills/help/SKILL.md

@@ -61,9 +61,9 @@ sandbox: `/cctest-intro` (start here), `/cctest-recipe-overview`, `/cctest-recip
 `/cctest-new-recipe-guide`, sandbox/instance management (`/cctest-setup-sandbox`,
 `/cctest-t1cc-start|stop`), and more — enumerate with `ls .opencode/skills | grep ^cctest-`.
 **Rule of thumb:** verifying/shipping against the CI pipeline → the cc-ci skills above;
-exploratory or hands-on recipe development on a test instance → `/cctest-*`. cc-ci policy
-overrides apply (auto-merge-style ARM flows need per-run operator opt-in; never touch cc-ci
-infra from an ARM skill). After a submodule bump run `scripts/gen-cctest-skills.py`.
+exploratory or hands-on recipe development on a test instance → `/cctest-*`. Policy is
+unified: recipe PRs are never agent-merged on either side (operator reviews + merges), and
+ARM skills never touch cc-ci infra. After a submodule bump run `scripts/gen-cctest-skills.py`.
 
 ## "What do you want to do?"