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>

docs/v3/twincat-backlog.md

@@ -0,0 +1,31 @@
+# TwinCAT driver — v3 backlog
+
+The v2 TwinCAT driver is considered solid: 28 integration tests (14 `[TwinCATFact]` +
+16-case `[TwinCATTheory]`) running live against the TCBSD fixture, 110 unit tests,
+three latent driver bugs shaken out (notification cycle units, `STRING(N)` mapper,
+bit-indexed BOOL path). Further work is deferred.
+
+Archived from `docs/drivers/TwinCAT-Test-Fixture.md` § Follow-up candidates.
+
+## Deferred items
+
+1. **TC2 coverage** — spin up a TC2 runtime (Windows CE IPC or legacy XAR)
+   and run the same suite; any delta surfaces. Blocked on hardware.
+
+2. **Notification coalescing under load** — run the subscribe test while
+   the PLC cycle is saturated (bump `lineSim` complexity, watch for
+   dropped notifications). Doable on current rig; deferred as lower
+   priority than v3 feature work.
+
+3. **Multi-hop AMS route** — add a test behind an IPC gateway with a
+   chained route entry. Blocked on hardware (gateway IPC).
+
+4. **License-rotation automation** — XAR's 7-day trial expires on
+   schedule. Either automate `TcActivate.exe /reactivate` via a scheduled
+   task on the VM (not officially supported; reportedly works for some
+   TC3 builds), or buy a paid runtime license (~$1k one-time per runtime
+   per CPU) to kill the rotation. Ops item, not code.
+
+5. **Lab rig** — cheapest IPC (CX7000 / CX9020) on a dedicated network;
+   the only route that covers TC2 + real EtherCAT I/O timing + cycle
+   jitter under CPU load. Blocked on hardware + budget.