refactor(fleet): #542 delete the dead fleet-status chain (broadcaster, SignalR bridge, hub, messages)

#542 filed FleetStatusBroadcaster as blind to site nodes since the Phase 6 per-cluster mesh
split: it derives "the fleet" from central's own Akka gossip ring, which after the split is
just central's own pair. Scoping the cross-mesh rewrite found the deeper truth — the whole
chain is dead end to end, so this deletes it rather than reviving it.

  - Zero consumers. FleetStatusBroadcaster published FleetStatusChanged on the DPS
    "fleet-status" topic; FleetStatusSignalRBridge forwarded it to FleetStatusHub
    ("/hubs/fleet-status"); nothing anywhere connected. The AdminUI bans self-connecting
    HubConnections, no browser JS subscribes, and /fleet (Fleet.razor) reads
    NodeDeploymentState from the ConfigDb plus IClusterRoleInfo on a 5 s poll instead.
  - Its second input never existed. DriverHostStatusHeartbeat had no production sender —
    only the broadcaster's own test told it — so CurrentRevision was always null and the
    30 s staleness -> Degraded flip could never fire.
  - Post-Phase-6 DPS is pair-local, so even the central-only view it did produce was an
    accident of topology rather than a design.

The fleet visibility that actually works is unchanged and already cross-mesh-correct:
/fleet over NodeDeploymentState, and the four Phase 5 per-node telemetry dials.

Precedent for deleting inert machinery rather than activating it: #522 (driver stability
tiers), #507 (discovered-node injection), #525 (GetMemoryFootprint).

Deleted: FleetStatusBroadcaster (+ its nested DriverHostStatusHeartbeat), its admin
singleton registration and FleetStatusBroadcasterKey, FleetStatusSignalRBridge and its
key, FleetStatusHub and its route mapping, and the FleetStatusChanged / FleetNodeStatus /
FleetNodeHealth messages. Both Fleet/ directories survive — ControlPlane keeps
ClusterNodeAddressReconciler, Commons keeps GetDiagnostics. Docs swept where they claimed
a fleet-status channel exists (Telemetry.md's Phase 5 non-migrated channels,
Configuration.md, CLAUDE.md); completed-program plan docs under docs/plans and docs/v2 are
left as the historical record they are.

Build 0 errors, 868 warnings — byte-identical to master's rebuild baseline.
ControlPlane.Tests 231/231, AdminUI.Tests 1109/1109.

Claude-Session: https://claude.ai/code/session_014WNM4vjoVksyyBraTXSZE1

tests/Server/ZB.MOM.WW.OtOpcUa.AdminUI.Tests/Hubs/TelemetryModeWiringTests.cs

@@ -16,12 +16,11 @@ namespace ZB.MOM.WW.OtOpcUa.AdminUI.Tests.Hubs;
 ///     Verifies the Phase 5 dark switch in <see cref="HubServiceCollectionExtensions.WithOtOpcUaSignalRBridges"/>:
 ///     <c>TelemetryDial:Mode = Dps</c> (default) spawns the four telemetry DPS bridge actors and NOT the
 ///     gRPC dial supervisor; <c>Grpc</c> spawns the dial supervisor and NONE of the four telemetry
-///     bridges. The fleet-status bridge (deferred / out of Phase 5 scope) is spawned in BOTH modes.
-///     The gate is proven on a real <see cref="ActorRegistry"/> from a started Akka host.
+///     bridges. The gate is proven on a real <see cref="ActorRegistry"/> from a started Akka host.
 /// </summary>
 public sealed class TelemetryModeWiringTests
 {
-    /// <summary>Dps mode: the four telemetry bridges + fleet bridge are registered; the dial supervisor is not.</summary>
+    /// <summary>Dps mode: the four telemetry bridges are registered; the dial supervisor is not.</summary>
     [Fact]
     public async Task Dps_mode_spawns_the_four_telemetry_bridges_and_not_the_dial_supervisor()
     {
@@ -31,7 +30,6 @@ public sealed class TelemetryModeWiringTests
         {
             var registry = host.Services.GetRequiredService<ActorRegistry>();
 
-            registry.TryGet<FleetStatusSignalRBridgeKey>(out _).ShouldBeTrue();
             registry.TryGet<AlertSignalRBridgeKey>(out _).ShouldBeTrue();
             registry.TryGet<ScriptLogSignalRBridgeKey>(out _).ShouldBeTrue();
             registry.TryGet<DriverStatusSignalRBridgeKey>(out _).ShouldBeTrue();
@@ -45,7 +43,7 @@ public sealed class TelemetryModeWiringTests
         }
     }
 
-    /// <summary>Grpc mode: the dial supervisor + fleet bridge are registered; none of the four telemetry bridges are.</summary>
+    /// <summary>Grpc mode: the dial supervisor is registered; none of the four telemetry bridges are.</summary>
     [Fact]
     public async Task Grpc_mode_spawns_the_dial_supervisor_and_none_of_the_four_telemetry_bridges()
     {
@@ -55,7 +53,6 @@ public sealed class TelemetryModeWiringTests
         {
             var registry = host.Services.GetRequiredService<ActorRegistry>();
 
-            registry.TryGet<FleetStatusSignalRBridgeKey>(out _).ShouldBeTrue();
             registry.TryGet<TelemetryDialSupervisorKey>(out _).ShouldBeTrue();
 
             registry.TryGet<AlertSignalRBridgeKey>(out _).ShouldBeFalse();

tests/Server/ZB.MOM.WW.OtOpcUa.ControlPlane.Tests/FleetStatusBroadcasterTests.cs

@@ -1,47 +0,0 @@
-using Akka.Actor;
-using Shouldly;
-using Xunit;
-using ZB.MOM.WW.OtOpcUa.Commons.Messages.Fleet;
-using ZB.MOM.WW.OtOpcUa.Commons.Types;
-using ZB.MOM.WW.OtOpcUa.ControlPlane.Fleet;
-using ZB.MOM.WW.OtOpcUa.ControlPlane.Tests.Harness;
-
-namespace ZB.MOM.WW.OtOpcUa.ControlPlane.Tests;
-
-public sealed class FleetStatusBroadcasterTests : ControlPlaneActorTestBase
-{
-    /// <summary>Verifies that the self member's join appears in the initial fleet status snapshot.</summary>
-    [Fact]
-    public void Self_member_up_lands_in_snapshot()
-    {
-        var probe = CreateTestProbe();
-        Sys.ActorOf(FleetStatusBroadcaster.Props(broadcast: msg => probe.Ref.Tell(msg)));
-
-        // The cluster self-joined in the harness — InitialStateAsEvents replays MemberUp for self.
-        var snapshot = probe.ExpectMsg<FleetStatusChanged>(TimeSpan.FromSeconds(5));
-        snapshot.Nodes.Count.ShouldBeGreaterThanOrEqualTo(1);
-        snapshot.Nodes.Any(n => n.Health == FleetNodeHealth.Healthy).ShouldBeTrue();
-    }
-
-    /// <summary>Verifies that heartbeat messages update the node revision in the next broadcast.</summary>
-    [Fact]
-    public void Heartbeat_updates_revision_in_next_snapshot()
-    {
-        var probe = CreateTestProbe();
-        var actor = Sys.ActorOf(FleetStatusBroadcaster.Props(broadcast: msg => probe.Ref.Tell(msg)));
-
-        // Drain the initial MemberUp snapshot.
-        probe.ExpectMsg<FleetStatusChanged>(TimeSpan.FromSeconds(5));
-
-        // Send a heartbeat for a node we know about (the self node from the cluster).
-        var selfHost = Akka.Cluster.Cluster.Get(Sys).SelfAddress.Host!;
-        var rev = RevisionHash.Parse(new string('c', 64));
-        actor.Tell(new FleetStatusBroadcaster.DriverHostStatusHeartbeat(NodeId.Parse(selfHost), rev));
-
-        // Wait for next periodic broadcast and assert the revision propagated.
-        var next = probe.FishForMessage<FleetStatusChanged>(
-            isMessage: m => m.Nodes.Any(n => n.CurrentRevision == rev),
-            max: TimeSpan.FromSeconds(10));
-        next.Nodes.Single(n => n.NodeId.Value == selfHost).CurrentRevision.ShouldBe(rev);
-    }
-}

tests/Server/ZB.MOM.WW.OtOpcUa.ControlPlane.Tests/RedundancyStateSingletonRehomeTests.cs

@@ -69,7 +69,7 @@ public sealed class RedundancyStateSingletonRehomeTests
 
         registry.TryGet<RedundancyStateActorKey>(out _).ShouldBeFalse(
             "the redundancy singleton was re-homed off the admin node onto every driver node (Phase 6)");
-        registry.TryGet<FleetStatusBroadcasterKey>(out _).ShouldBeTrue(
+        registry.TryGet<AuditWriterActorKey>(out _).ShouldBeTrue(
             "the remaining admin singletons must still register");
     }