- Add State_GPU message to the proto with utilization and memory fields
- Add HostState.GPUs with conversion in both PB() and PB2State()
- Keep the existing gpu field populated so older agents keep working
Regenerated with protoc-gen-go v1.34.2 / protoc v5.29.3 to match the
existing files; nezha_grpc.pb.go is untouched since the service is
unchanged.
Closes#1217