test: smoke scripts fail when they stop before their last check

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

tests/Integration/mcp-smoke.sh

@@ -18,7 +18,7 @@ cleanup() {
   cleanup_app_passwords_for lit-smoke-sub
   wp user delete lit-smoke-sub --yes >/dev/null 2>&1 || true
 }
-trap cleanup EXIT
+trap 'rc=$?; cleanup; guard_exit "$rc" || exit $?' EXIT
 
 # 0. Booting REST triggers no _doing_it_wrong(). A regression in the
 # unhook-before-create ordering (ServerRegistrar::createServer()) would
@@ -156,4 +156,4 @@ echo "$SUB_META" | grep -Eq 'lacks required capability|nicht freigegeben' \
   || fail "execute-ability denial lacks role-gate message: $SUB_META"
 pass "role gate blocks subscriber (direct tool and meta-tool)"
 
-echo "ALL CHECKS PASSED"
+finish