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.

src/ZB.MOM.WW.ScadaBridge.Communication/ReconcileService.cs

@@ -8,8 +8,8 @@ namespace ZB.MOM.WW.ScadaBridge.Communication;
 
 /// <summary>
 /// Central-side startup-reconciliation handler. A site node, on startup, reports its
-/// local deployed inventory via <see cref="ReconcileSiteRequest"/> (delivered over
-/// ClusterClient to <see cref="Actors.CentralCommunicationActor"/>); this service diffs
+/// local deployed inventory via <see cref="ReconcileSiteRequest"/> (delivered over the
+/// control plane to <see cref="Actors.CentralCommunicationActor"/>); this service diffs
 /// it against central's expected deployed set and replies with fresh fetch tokens for the
 /// gap — instances the node is missing or has at a stale revision — plus the orphan names
 /// (present locally but no longer deployed centrally, which the node only logs).