Writes conformance/cases/producer.json: the queue messages Ankusa.Sink.Message.encode/3 produces for a fixed set of hooks, each paired with what an SDK's decode_message must return for it (feature message.producer).

mix ankusa.conformance.gen [--out PATH]

The SDKs' own vectors are decoder-only: they prove an SDK reads the messages somebody wrote by hand. These prove it reads the messages core writes. The file is generated, never edited: mise run check:conformance (check.mjs) runs this task into a temporary file and fails when the result differs from the checked-in one, so a field added to, removed from or changed in encode/3 fails the build until the vectors are regenerated and every SDK decodes them.

--out defaults to conformance/cases/producer.json of the repository (run the task from packages/ankusa). The output is deterministic: fixed ids, times and bodies, keys in a fixed order.