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/DriverLifecycle.md

@@ -89,8 +89,9 @@ Members:
 Implementations: every driver ships a `*DriverProbe` in its driver project
 (e.g.
 [`Driver.Modbus/ModbusDriverProbe.cs`](../src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Modbus/ModbusDriverProbe.cs)
-does a bare socket open/close), plus the Wonderware historian's
-`WonderwareHistorianDriverProbe`.
+does a bare socket open/close). The historian backend is the external
+HistorianGateway (consumed as a gRPC client package, not an `IDriver`), so it
+has no driver probe.
 
 Flow: the AdminUI's `AdminProbeService`
 ([`AdminUI/Clients/AdminProbeService.cs`](../src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Clients/AdminProbeService.cs))
@@ -203,8 +204,8 @@ lifecycle. This is distinct from the driver capability `IHistoryProvider`:
 - `IHistoryProvider` is a *driver capability* — the server dispatches to it via
   the driver instance.
 - `IHistorianDataSource` is a *server registration* — the server resolves it by
-  namespace and calls it directly, so one historian (e.g. Wonderware) can serve
-  many drivers' nodes, and drivers can restart without dropping history
+  namespace and calls it directly, so one historian (the HistorianGateway) can
+  serve many drivers' nodes, and drivers can restart without dropping history
   availability.
 
 The interface is `: IDisposable` and declares the full read surface as
@@ -230,20 +231,18 @@ All values use the shared `DataValueSnapshot` / `HistoricalEvent` shapes;
 backend-specific quality/type encodings are translated to OPC UA `StatusCode`
 uints inside the data source.
 
-Implementations:
+Implementation:
 
-- `WonderwareHistorianClient`
-  ([`Driver.Historian.Wonderware.Client/WonderwareHistorianClient.cs`](../src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Wonderware.Client/WonderwareHistorianClient.cs))
-  — the .NET 10 client that talks to the Wonderware historian sidecar over
-  TCP (optional TLS). It implements both `IHistorianDataSource` (read paths) and
-  `IAlarmHistorianWriter` (the alarm-event drain target; see
+- `GatewayHistorianDataSource`
+  ([`Driver.Historian.Gateway/GatewayHistorianDataSource.cs`](../src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Gateway/GatewayHistorianDataSource.cs))
+  — the read backend that talks gRPC to the external `ZB.MOM.WW.HistorianGateway`
+  (via the `ZB.MOM.WW.HistorianGateway.Client` package, behind the
+  `IHistorianGatewayClient` seam). The alarm-event drain target is the separate
+  `GatewayAlarmHistorianWriter` (the gateway `SendEvent` path; see
   [AlarmHistorian.md](AlarmHistorian.md)).
-- `HistorianDataSource`
-  ([`Driver.Historian.Wonderware/Backend/HistorianDataSource.cs`](../src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.Wonderware/Backend/HistorianDataSource.cs))
-  — the in-process backend implementation behind the sidecar.
 
-The optional Wonderware historian sidecar setup is described in
-[ServiceHosting.md](ServiceHosting.md).
+The HistorianGateway is the sole historian backend; its config keys and
+deployment prerequisites are in [Historian.md](Historian.md).
 
 ---
 
@@ -288,7 +287,7 @@ Folders:
 - [ReadWriteOperations.md](ReadWriteOperations.md) — the driver *capability*
   interfaces (read/write/subscribe) and resilience pipeline.
 - [ServiceHosting.md](ServiceHosting.md) — role gating, the Akka cluster, and
-  the optional Wonderware historian sidecar.
+  the external HistorianGateway backend.
 - [AlarmHistorian.md](AlarmHistorian.md) — the store-and-forward SQLite alarm
   sink that drains to `IAlarmHistorianWriter`.
 - [Redundancy.md](Redundancy.md) — driver stability tiers in the redundancy