Each service now exposes its help catalog via Service::help_topics; the
engine collects them into a network-wide index on Network, reachable
through two new NetView methods. HelpServ uses it: HELP <service>
[command] (or a bare service name) serves any service's per-command
help, bare HELP lists the services, and its own ticket commands still
work. No cross-crate dependency: the catalog flows through the SDK's
NetView, keeping every module dependent only on echo-api.
Jean
fcca8e4e3b