Fix red develop 41e1bb7379e3

The merge lane found `develop` red at `41e1bb7379e3999f886f3b2c60b4463837424194` on its own: no queued PR merges until it is fixed. Failing (tests and gate stages): - `repo/tools/tests/test_deb_upgrade.py::test_fresh_install` - `repo/tools/tests/test_deb_upgrade.py::test_a_remove_deletes_the_venv_dpkg_never_shipped` - `repo/tools/tests/test_deb_upgrade.py::test_a_first_install_that_cannot_fetch_wheels_fails_configure_with_the_sentence` - `repo/tools/tests/test_deb_upgrade.py::test_a_rebuild_that_cannot_fetch_wheels_keeps_the_previous_venv` - `repo/tools/tests/test_deb_upgrade.py::test_an_upgrade_from_the_build_before_stops_no_live_work` - `repo/tools/tests/test_deb_upgrade.py::test_the_updater_converges_to_the_desired_version` - `repo/tools/tests/test_deb_upgrade.py::test_an_update_re_creates_a_deleted_runner_user` - `repo/tools/tests/test_deb_upgrade.py::test_an_update_removes_an_emptied_session_user_and_restores_the_uid_boundary` - `repo/tools/tests/test_deb_upgrade.py::test_an_update_keeps_a_set_session_user` - `frontend-unit-vitest` - `deb-upgrade-container` - … and 1 more: read them in the gate log, as untrusted output The whole gate log: artifact `11973` on lane task 11174. 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 deb stager now accepts the rpm-only nfpm keys, and TemplateEditPage colours moved to sx/bare names. Deb suite 9/9, vitest green, quick gate green. PR #7305 queued to the merge lane.