Disable WebSocket compression in kas
Disable WebSocket compression in kas. We already always use gRPC compression between agentk and kas (and nowhere else).
I've disabled compression on the agentk side, but it makes sense to do that on kas side too as WebSocket is a hop-to-hop protocol. Also, we cannot make people upgrade ASAP so doing it in kas fixes it for all.
Relates to #424 (closed).