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>

scripts/e2e/test-all.ps1

@@ -189,6 +189,33 @@ if ($galaxy) {
 }
 else { $summary["galaxy"] = "SKIP (no config entry)" }
 
+# ---------------------------------------------------------------------------
+# OPC UA Client (gateway driver)
+# ---------------------------------------------------------------------------
+
+$opcuaclient = Get-Or $config "opcuaclient"
+if ($opcuaclient) {
+    Write-Header "== OPC UA CLIENT =="
+    Run-Suite "opcuaclient" {
+        & "$PSScriptRoot/test-opcuaclient.ps1" `
+            -RemoteUrl             (Get-Or $opcuaclient "remoteUrl" "opc.tcp://localhost:50000") `
+            -OpcUaUrl              (Get-Or $opcuaclient "opcUaUrl" $OpcUaUrl) `
+            -RemoteNodeId          (Get-Or $opcuaclient "remoteNodeId" "ns=3;s=FastUInt1") `
+            -BridgeNodeId          $opcuaclient["bridgeNodeId"] `
+            -WritableRemoteNodeId  (Get-Or $opcuaclient "writableRemoteNodeId" "") `
+            -WritableBridgeNodeId  (Get-Or $opcuaclient "writableBridgeNodeId" "") `
+            -BridgeRootNodeId      (Get-Or $opcuaclient "bridgeRootNodeId" "i=85") `
+            -BrowseDepth           (Get-Or $opcuaclient "browseDepth" 3) `
+            -BrowseMinNodes        (Get-Or $opcuaclient "browseMinNodes" 5) `
+            -AlarmNodeId           (Get-Or $opcuaclient "alarmNodeId" "") `
+            -AlarmWaitSec          (Get-Or $opcuaclient "alarmWaitSec" 15) `
+            -HistoryNodeId         (Get-Or $opcuaclient "historyNodeId" "") `
+            -HistoryLookbackSec    (Get-Or $opcuaclient "historyLookbackSec" 3600) `
+            -ChangeWaitSec         (Get-Or $opcuaclient "changeWaitSec" 8)
+    }
+}
+else { $summary["opcuaclient"] = "SKIP (no config entry)" }
+
 $phase7 = Get-Or $config "phase7"
 if ($phase7) {
     Write-Header "== PHASE 7 virtual tags + scripted alarms =="
@@ -220,7 +247,9 @@ $summary.GetEnumerator() | ForEach-Object {
     Write-Host ("  {0,-10} {1}" -f $_.Key, $_.Value) -ForegroundColor $color
 }
 
-$failed = ($summary.Values | Where-Object { $_ -eq "FAIL" }).Count
+# @() wrap — Where-Object returns $null / a single scalar for 0-or-1 matches,
+# and .Count on either trips Set-StrictMode -Version 3.0.
+$failed = @($summary.Values | Where-Object { $_ -eq "FAIL" }).Count
 if ($failed -gt 0) {
     Write-Host "$failed suite(s) failed." -ForegroundColor Red
     exit 1