API Versioning

Use an explicit major API version.
Prefer additive fields and events.
Clients must tolerate unknown fields and events.
Breaking changes require a new major version, fixtures, migration notes, and coordinated releases.
Each release records minimum compatible client and server versions.
GET /api/v1/server/info publishes minimum_client_version and maximum_client_version; clients must use these fields to detect an incompatible pairing before enabling authenticated controls.