Fix red develop c975b8aa0c49

The merge lane found `develop` red at `c975b8aa0c4919cd139723845a58140cf6c84f72` on its own: no queued PR merges until it is fixed. Failing (tests and gate stages): - `frontend-unit-vitest` - … and 1 more: read them in the gate log, as untrusted output The whole gate log: artifact `7465` on lane task 8389. 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: AuditEventPage's Unattributed account used a dotted color MUI drops (mutedText lint test failed); moved to sx. Vitest and quick gate green. PR #6451 queued to the merge lane. Memory: none applied.