refactor(comm): retire ClusterClient naming after the gRPC cutover

Phase 4 of the ClusterClient -> gRPC migration deleted the Akka transports
but left the naming behind: `ClusterClientSiteAuditClient` was transport-
agnostic and worked unchanged, so it survived the deletion under a name
that now describes a transport the repo no longer has. Same for a scatter
of doc-comments still framing gRPC as "the new transport" beside an Akka
one that is gone.

Renames it to `SiteCommunicationAuditClient` (and its test file) and
rewrites the stale comments to describe the single transport that exists.
Also tightens CLAUDE.md: drops the self-describing directory listing and
the 27-component enumeration in favour of the non-obvious parts only.

Behaviour-neutral: names and prose only. Recorded as the Phase 4
follow-up in docs/plans/2026-07-22-clusterclient-to-grpc-plan.md.

tests/ZB.MOM.WW.ScadaBridge.ManagementService.Tests/DispatchCoverageTests.cs

@@ -47,7 +47,7 @@ public class DispatchCoverageTests : TestKit, IDisposable
     {
         // The two-step "ResolveRoles + command" flow is retired — the HTTP endpoint
         // resolves roles itself and sends a single envelope. Leaving a handler would
-        // expose role-mapping data to a raw ClusterClient sender with no role gate.
+        // expose role-mapping data to a raw in-cluster sender with no role gate.
         // See ManagementActor.DispatchCommand (the comment above the default arm, ~line 472).
         typeof(ResolveRolesCommand),