Kura serves HTTP and REAPI gRPC on a single co-hosted listener

Kura now serves the HTTP cache API and the REAPI gRPC surface on the same listener, so you can point the Tuist/Bazel cache URL at a single address. Self-hosting setups no longer need a separate gRPC port, TLS certificate, or listener configuration: KURA_PORT covers both protocols, and KURA_HTTPS_PORT covers both over TLS when certificates are configured. The dedicated gRPC listener, KURA_GRPC_PORT, and KURA_GRPC_TLS_* settings have been removed from the deployment surface.