TestBuildClientPushEventCoversCatalog required every catalog kind to
encode through a FlatBuffers `preMarshaledEvent`. game.turn.ready
intentionally rides on the JSON fallback because its payload is just
`{game_id, turn}` and the only consumer (Phase 24 UI handler) parses
JSON inline. Make the policy explicit through a jsonFriendlyKinds
allow-list so the test still asserts each kind is covered and a future
producer that picks the wrong encoding fails loudly.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Ilia Denisov