Why: The follow-up CI exposed that backend #188 broke the Dev multi-instance suite: serve --mock seeded runtime.mock at the user scope, which system-managed settings now reject, so instances never became healthy. Backend #190 seeds the startup flag into the system scope; this PR repins and drops the now-invalid alice user-scope write. Evidence: Backend #190 CI success at head 0af1ebc (GATE); this PR's composite CI re-runs make test-multi-instance (GATE for the fix). Impact: backend pin 741da4a; multi-instance test comments updated to the system-managed regime. Refs: Backend #188, #190.