byUserId

Sorts participants by their ParticipantState.userId ascending (string compare).

Intended as a deterministic last-resort tiebreaker so participants with otherwise equal signals (no dominant-speaker, no pin, no raised hand, etc.) don't shuffle around between sort passes. Mirrors iOS's userId comparator used in the trailing ifInvisibleBy(userId) of every iOS preset.

Note: this is lexicographic string compare — for production user IDs (UUIDs or arbitrary strings) the resulting order is meaningless to humans but is stable across re-sorts.