Shared schemas and primitives for Dynamo data generation.
Today the crate hosts the Mooncake replay JSONL row schema, the rolling
block-hash-to-id mapper, and the JSONL writer used by trace producers
(e.g. the Claude exporter in dynamo-bench) and trace consumers
(e.g. dynamo-mocker). A single MooncakeRow type with both Serialize
and Deserialize derives keeps the producer and consumer in lockstep and
eliminates the schema drift that previously existed between two private
copies of the schema.