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

Kura now serves both its HTTP cache API and the REAPI gRPC surface on a single co-hosted listener, dispatched by path on the same port. As a result, tuist bazel setup (driven by TUIST_CACHE_ENDPOINT) now derives a working gRPC target from the single cache URL, fixing the case where REAPI GetCapabilities was hitting the plain-HTTP listener and runners fell back to a cold cache. Self-hosters need only configure one cache port (default 4000, or 4443 when TLS is enabled), and can drop the old KURA_GRPC_PORT / KURA_GRPC_TLS_* settings. Public Bazel/CLI dial addresses stay the same.