docs(historian-gateway): document gateway backend, config keys, EnsureTags hook, known gates; retire Wonderware from docs

HistorianGateway is now the sole historian backend (read + alarm SendEvent +
continuous WriteLiveValues). Document the final state and retire the Wonderware
sidecar from the docs/config/labels:

- CLAUDE.md: rewrite the Historian section — ServerHistorian /
  ContinuousHistorization / AlarmHistorian config keys, the IHistorianProvisioning
  EnsureTags hook, the GatewayAlarmHistorianWriter SendEvent path + ReadEvents
  dependency on gateway RuntimeDb:EventReadsEnabled=true, gateway-side
  prerequisites (RuntimeDb flags + historian:read/write/tags:write scopes),
  migration note, and two KNOWN-LIMITATION callouts (live-validation gate +
  empty historized-ref-set recorder follow-on).
- appsettings.json: fix the stale ServerHistorian block (Host/Port/SharedSecret/
  ServerCertThumbprint -> Endpoint/ApiKey/UseTls/AllowUntrustedServerCertificate/
  CaCertificatePath/CallTimeout, keep MaxTieClusterOverfetch); add a disabled
  ContinuousHistorization block; prune the orphaned Wonderware keys from
  AlarmHistorian (keep the SQLite knobs). ApiKey env-supplied via
  ServerHistorian__ApiKey (commented; valid strict JSON via _comment keys).
- README.md + docs (Historian.md, AlarmHistorian.md, Configuration.md,
  ServiceHosting.md, DriverLifecycle.md, drivers/README.md, Uns.md, VirtualTags.md,
  AlarmTracking.md, Client.UI.md, README.md, TestConnectProbes.md): retire the
  Wonderware historian backend from current-backend descriptions; fix the stale
  ServerHistorian/AlarmHistorian config tables (now gateway shape); convert
  drivers/Historian.Wonderware.md to a retired stub pointing at the gateway.
- Source/UI labels (descriptive text only, no behavior change):
  OtOpcUaServerHostedService.cs, HistoryPaging.cs, OtOpcUaSdkServer.cs,
  HistorianAdapterActor.cs, VirtualTagModal.razor, ScriptedAlarmModal.razor,
  AlarmsHistorian.razor now name the HistorianGateway backend.

Build clean (0 errors); AdminUI.Tests green (514 passed).

Claude-Session: https://claude.ai/code/session_012SDSQ3AcaXqPcBtDESBRii

docs/ServiceHosting.md

@@ -2,14 +2,15 @@
 
 ## Overview
 
-A production OtOpcUa deployment runs **one binary per node**, plus the optional Wonderware historian sidecar:
+A production OtOpcUa deployment runs **one binary per node**. The historian backend is the external
+`ZB.MOM.WW.HistorianGateway`, deployed separately (not installed by this repo's scripts):
 
 | Process | Project | Runtime | Platform | Responsibility |
 |---|---|---|---|---|
 | **OtOpcUa Host** | `src/Server/ZB.MOM.WW.OtOpcUa.Host` | .NET 10 | AnyCPU | Single fused binary. `OTOPCUA_ROLES` env decides what to mount: `admin` (Blazor + auth + control-plane singletons), `driver` (OPC UA endpoint + per-driver actors), or both. |
-| **OtOpcUa Wonderware Historian** *(optional)* | `src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Wonderware` | .NET Framework 4.8 | x64 (64-bit) | Out-of-process sidecar exposing the Wonderware Historian SDK over TCP (optional TLS). Required only when `AlarmHistorian:Enabled=true`. May run on the same machine or a remote host. |
+| **ZB.MOM.WW.HistorianGateway** *(external — separate deployment)* | not in this repo | .NET 10 | — | The sole historian backend. OtOpcUa talks gRPC to it (via the `ZB.MOM.WW.HistorianGateway.Client` package) for HistoryRead, alarm `SendEvent`, and continuous `WriteLiveValues`. Must run `RuntimeDb:Enabled=true` + `RuntimeDb:EventReadsEnabled=true`; the API key must carry `historian:read` + `historian:write` + `historian:tags:write`. |
 
-Galaxy access still uses the separately-installed **mxaccessgw** sidecar (see `docs/v2/Galaxy.ParityRig.md`); the gateway owns the MXAccess COM bitness constraint (its worker is x86 net48). Nothing in the OtOpcUa repo carries that constraint anymore.
+Galaxy access still uses the separately-installed **mxaccessgw** sidecar (see `docs/v2/Galaxy.ParityRig.md`); the gateway owns the MXAccess COM bitness constraint (its worker is x86 net48). Nothing in the OtOpcUa repo carries that constraint anymore. (The bespoke Wonderware historian sidecar this deployment used to ship was retired — see [drivers/Historian.Wonderware.md](drivers/Historian.Wonderware.md).)
 
 > **v2 change.** v1's separate `OtOpcUa.Server` + `OtOpcUa.Admin` Windows services merged into a single role-gated `OtOpcUa.Host` binary. Two installers became one (with a `-Roles` parameter). The whole DI graph is composed in `OtOpcUa.Host/Program.cs`; per-role wiring is conditional on the env var.
 
@@ -72,14 +73,20 @@ Both admin and driver nodes expose:
 
 Used by Traefik for the active-leader-only routing pattern (see [Architecture-v2.md](v2/Architecture-v2.md)).
 
-## OtOpcUa Wonderware Historian (optional)
+## Historian backend (HistorianGateway — external)
 
-IPC contract types live in `src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Wonderware.Client.Contracts/`; sidecar TCP server in `src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Wonderware/Ipc/`. The sidecar listens on TCP port 32569 by default; `Install-Services.ps1 -InstallWonderwareHistorian` adds the Windows Firewall inbound rule. The host and sidecar may run on different machines — configure `AlarmHistorian:Host` + `AlarmHistorian:Port` (and optionally `AlarmHistorian:UseTls`) on the OtOpcUa host side. See [Historian.Wonderware.md](drivers/Historian.Wonderware.md) for the full transport and security reference.
+The historian backend is the external `ZB.MOM.WW.HistorianGateway`, deployed and operated separately (not
+installed by `Install-Services.ps1`). OtOpcUa connects to it over gRPC via the
+`ZB.MOM.WW.HistorianGateway.Client` package — configure the `ServerHistorian:Endpoint` (`https://host:5222`)
+and supply `ServerHistorian__ApiKey` via the environment on the OtOpcUa host side. The gateway must run with
+`RuntimeDb:Enabled=true` + `RuntimeDb:EventReadsEnabled=true` and an API key carrying `historian:read` +
+`historian:write` + `historian:tags:write`. See [Historian.md](Historian.md) for the full config-key and
+deployment-prerequisite reference. (The retired Wonderware TCP sidecar: [Historian.Wonderware.md](drivers/Historian.Wonderware.md).)
 
 ## Install / Uninstall
 
 - `scripts/install/Install-Services.ps1 -Roles admin,driver` — installs `OtOpcUaHost`.
-- `scripts/install/Uninstall-Services.ps1` — stops + removes the host service (and the historian sidecar if installed).
+- `scripts/install/Uninstall-Services.ps1` — stops + removes the host service. (The historian backend is the external HistorianGateway — not installed/removed by these scripts.)
 
 ## Logging