Fix red develop 3111198384f9

The merge lane found `develop` red at `3111198384f9831987f75fd1e657ec585eaafc8f` on its own: no queued PR merges until it is fixed. Failing (tests and gate stages): - `tests/test_acp_host.py::test_an_elicitation_this_client_cannot_carry_is_declined_per_spec_never_an_error[params1]` - `jaahd-unit-pytest` The whole gate log: artifact `9771` on lane task 9900. Make `develop` pass its full gate again. Open a PR as usual: the merge lane merges a PR that fixes some of these and adds no failure even while `develop` is red.

Fixed red develop: the test_acp_host elicitation stub now accepts the question_preamble kwarg added in 0408c99a8. Test-only, quick gate green, PR #6866 queued to the lane. 4 test_agent_launch failures seen only on this host are noted in the report. Memory: none applied.