Base path under which gRPC/Connect services are served. Defaults to the root ('/', M70i). A gRPC-family client derives its path from the fully-qualified method name alone and has no prefix option, so a prefixed default puts every procedure at an address no such client asks for. At the root, unknown paths fall through to Hono and only registered procedure paths are claimed. This makes Connect and gRPC-Web reachable at their natural addresses; native application/grpc reaches the server too but is deliberately refused with a Trailers-Only UNIMPLEMENTED. Pass '/grpc' to restore the pre-M70i prefix.