task-galaxy-e2e branch — non-FOCAS work-in-progress snapshot

Catch-all commit for pending work on the task-galaxy-e2e branch that
wasn't part of the FOCAS migration. Grouping by topic so future per-topic
commits can be cherry-picked if needed.

TwinCAT
- src/.../Driver.TwinCAT/AdsTwinCATClient.cs + TwinCATDriverFactoryExtensions.cs:
  factory-registration extensions + ADS client refinements.
- src/.../Driver.TwinCAT.Cli/Commands/BrowseCommand.cs: new browse command
  for the TwinCAT test-client CLI.
- tests/.../Driver.TwinCAT.IntegrationTests/TwinCAT3SmokeTests.cs + TwinCatProject/:
  fixture scaffold with a minimal POU + README pointing at the TCBSD/ESXi
  VM for e2e.
- docs/Driver.TwinCAT.Cli.md + docs/drivers/TwinCAT-Test-Fixture.md:
  documentation for the above.
- docs/v3/twincat-backlog.md: forward-looking backlog seed.

Admin UI + fleet status
- src/.../Admin/Components/Pages/Clusters/DriversTab.razor + Hosts.razor:
  UI refresh for fleet-status rendering.
- src/.../Admin/Hubs/FleetStatusHub.cs + FleetStatusPoller.cs +
  Admin/Program.cs: SignalR hub + poller plumbing for live fleet data.
- tests/.../Admin.Tests/FleetStatusPollerTests.cs: poller coverage.

Server + redundancy runtime (Phase 6.3 follow-ups)
- src/.../Server/Hosting/RedundancyPublisherHostedService.cs: HostedService
  that owns the RedundancyStatePublisher lifecycle + wires peer reachability.
- src/.../Server/Redundancy/ServerRedundancyNodeWriter.cs: OPC UA
  variable-node writer binding ServiceLevel + ServerUriArray to the
  publisher's events.
- src/.../Server/Program.cs + Server.csproj: hosted-service registration.
- tests/.../Server.Tests/ServerRedundancyNodeWriterTests.cs +
  Server.Tests.csproj: coverage for the above.

Configuration
- src/.../Configuration/Validation/DraftValidator.cs +
  tests/.../Configuration.Tests/DraftValidatorTests.cs: draft-validation
  refinements.

E2E scripts (shared infrastructure)
- scripts/e2e/README.md + _common.ps1 + test-all.ps1: shared helpers + the
  all-drivers test-all runner.
- scripts/e2e/test-opcuaclient.ps1: OPC UA Client e2e runner.

Docs
- docs/v2/implementation/phase-6-{1,2,3,4}*.md + exit-gate-phase-{3,7}.md:
  phase-gate + implementation doc updates.
- docs/v2/plan.md: top-level plan refresh.
- docs/v2/redundancy-interop-playbook.md: client interop playbook for the
  Phase 6.3 redundancy-runtime work.

Two orphan FOCAS docs remain on disk but deliberately unstaged —
docs/v2/focas-deployment.md and docs/v2/implementation/focas-simulator-plan.md
describe the now-retired Tier-C topology and should either be rewritten
or deleted in a follow-up.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/ZB.MOM.WW.OtOpcUa.Configuration.Tests/DraftValidatorTests.cs

@@ -145,4 +145,91 @@ public sealed class DraftValidatorTests
         errors.ShouldContain(e => e.Code == "EquipmentIdNotDerived");
         errors.ShouldContain(e => e.Code == "UnsSegmentInvalid");
     }
+
+    // ------------------------------------------------------------------------------------
+    // Phase 6.3 task #148 part 2 — ValidateClusterTopology
+    // ------------------------------------------------------------------------------------
+
+    [Theory]
+    [InlineData(1, RedundancyMode.None, 1, 0)]  // single-node standalone — ok
+    [InlineData(2, RedundancyMode.Warm, 2, 0)]  // 2-node warm — ok
+    [InlineData(2, RedundancyMode.Hot,  2, 0)]  // 2-node hot — ok
+    [InlineData(1, RedundancyMode.Warm, 1, 1)]  // declared mismatch — should flag
+    [InlineData(2, RedundancyMode.None, 2, 1)]  // None with 2 nodes — should flag
+    public void ValidateClusterTopology_checks_declared_pair(
+        byte nodeCount, RedundancyMode mode, int enabledNodes, int expectedDeclaredErrors)
+    {
+        var cluster = BuildCluster(nodeCount: nodeCount, mode: mode);
+        var nodes = Enumerable.Range(0, enabledNodes)
+            .Select(i => BuildNode($"n-{i}", enabled: true, role: i == 0 ? RedundancyRole.Primary : RedundancyRole.Secondary))
+            .ToList();
+
+        var errors = DraftValidator.ValidateClusterTopology(cluster, nodes);
+        errors.Count(e => e.Code == "ClusterRedundancyModeInvalid").ShouldBe(expectedDeclaredErrors);
+    }
+
+    [Fact]
+    public void ValidateClusterTopology_flags_disabled_node_mismatch()
+    {
+        // Declared 2 + Hot, but one node disabled — runtime would boot InvalidTopology.
+        var cluster = BuildCluster(nodeCount: 2, mode: RedundancyMode.Hot);
+        var nodes = new[]
+        {
+            BuildNode("primary", enabled: true,  role: RedundancyRole.Primary),
+            BuildNode("backup",  enabled: false, role: RedundancyRole.Secondary),
+        };
+
+        var errors = DraftValidator.ValidateClusterTopology(cluster, nodes);
+        errors.ShouldContain(e => e.Code == "ClusterEnabledNodeCountMismatch");
+    }
+
+    [Fact]
+    public void ValidateClusterTopology_flags_multiple_Primary()
+    {
+        var cluster = BuildCluster(nodeCount: 2, mode: RedundancyMode.Hot);
+        var nodes = new[]
+        {
+            BuildNode("a", enabled: true, role: RedundancyRole.Primary),
+            BuildNode("b", enabled: true, role: RedundancyRole.Primary),
+        };
+
+        var errors = DraftValidator.ValidateClusterTopology(cluster, nodes);
+        errors.ShouldContain(e => e.Code == "ClusterMultiplePrimary");
+    }
+
+    [Fact]
+    public void ValidateClusterTopology_returns_no_errors_on_valid_standalone()
+    {
+        var cluster = BuildCluster(nodeCount: 1, mode: RedundancyMode.None);
+        var nodes = new[] { BuildNode("only", enabled: true, role: RedundancyRole.Primary) };
+
+        var errors = DraftValidator.ValidateClusterTopology(cluster, nodes);
+        errors.ShouldBeEmpty();
+    }
+
+    private static ServerCluster BuildCluster(byte nodeCount, RedundancyMode mode) => new()
+    {
+        ClusterId = "c-test",
+        Name = "Test",
+        Enterprise = "zb",
+        Site = "dev",
+        NodeCount = nodeCount,
+        RedundancyMode = mode,
+        Enabled = true,
+        CreatedBy = "t",
+    };
+
+    private static ClusterNode BuildNode(string id, bool enabled, RedundancyRole role) => new()
+    {
+        NodeId = id,
+        ClusterId = "c-test",
+        RedundancyRole = role,
+        Host = "localhost",
+        OpcUaPort = 4840,
+        DashboardPort = 5001,
+        ApplicationUri = $"urn:{id}",
+        ServiceLevelBase = 200,
+        Enabled = enabled,
+        CreatedBy = "t",
+    };
 }