Snapshot/delta JSON publishing over moq-net tracks.
A JSON value is published over a track as a series of groups, where each group is self-contained: its first frame is a full snapshot and any following frames are RFC 7396 JSON Merge Patch deltas applied in order. A consumer jumps to the newest group, reads the snapshot, and applies the deltas, so a late joiner never needs older groups.
Deltas are controlled by [ProducerConfig::delta_ratio]. A ratio of 0 disables them, so every
change is a fresh snapshot group, matching a plain "one JSON blob per group" track.