Phase 0 — mechanical rename ZB.MOM.WW.LmxOpcUa.* → ZB.MOM.WW.OtOpcUa.*

Renames all 11 projects (5 src + 6 tests), the .slnx solution file, all source-file namespaces, all axaml namespace references, and all v1 documentation references in CLAUDE.md and docs/*.md (excluding docs/v2/ which is already in OtOpcUa form). Also updates the TopShelf service registration name from "LmxOpcUa" to "OtOpcUa" per Phase 0 Task 0.6.

Preserves runtime identifiers per Phase 0 Out-of-Scope rules to avoid breaking v1/v2 client trust during coexistence: OPC UA `ApplicationUri` defaults (`urn:{GalaxyName}:LmxOpcUa`), server `EndpointPath` (`/LmxOpcUa`), `ServerName` default (feeds cert subject CN), `MxAccessConfiguration.ClientName` default (defensive — stays "LmxOpcUa" for MxAccess audit-trail consistency), client OPC UA identifiers (`ApplicationName = "LmxOpcUaClient"`, `ApplicationUri = "urn:localhost:LmxOpcUaClient"`, cert directory `%LocalAppData%\LmxOpcUaClient\pki\`), and the `LmxOpcUaServer` class name (class rename out of Phase 0 scope per Task 0.5 sed pattern; happens in Phase 1 alongside `LmxNodeManager → GenericDriverNodeManager` Core extraction). 23 LmxOpcUa references retained, all enumerated and justified in `docs/v2/implementation/exit-gate-phase-0.md`.

Build clean: 0 errors, 30 warnings (lower than baseline 167). Tests at strict improvement over baseline: 821 passing / 1 failing vs baseline 820 / 2 (one flaky pre-existing failure passed this run; the other still fails — both pre-existing and unrelated to the rename). `Client.UI.Tests`, `Historian.Aveva.Tests`, `Client.Shared.Tests`, `IntegrationTests` all match baseline exactly. Exit gate compliance results recorded in `docs/v2/implementation/exit-gate-phase-0.md` with all 7 checks PASS or DEFERRED-to-PR-review (#7 service install verification needs Windows service permissions on the reviewer's box).

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

src/ZB.MOM.WW.OtOpcUa.Host/Historian/HistorianClusterNodeState.cs

@@ -0,0 +1,49 @@
+using System;
+
+namespace ZB.MOM.WW.OtOpcUa.Host.Historian
+{
+    /// <summary>
+    ///     Point-in-time state of a single historian cluster node. One entry per configured node is
+    ///     surfaced inside <see cref="HistorianHealthSnapshot"/> so the status dashboard can render
+    ///     per-node health and operators can see which nodes are in cooldown.
+    /// </summary>
+    public sealed class HistorianClusterNodeState
+    {
+        /// <summary>
+        ///     Gets or sets the configured node hostname exactly as it appears in
+        ///     <c>HistorianConfiguration.ServerNames</c>.
+        /// </summary>
+        public string Name { get; set; } = "";
+
+        /// <summary>
+        ///     Gets or sets a value indicating whether the node is currently eligible for new connection
+        ///     attempts. <see langword="false"/> means the node is in its post-failure cooldown window
+        ///     and the picker is skipping it.
+        /// </summary>
+        public bool IsHealthy { get; set; }
+
+        /// <summary>
+        ///     Gets or sets the UTC timestamp at which the node's cooldown expires, or
+        ///     <see langword="null"/> when the node is not in cooldown.
+        /// </summary>
+        public DateTime? CooldownUntil { get; set; }
+
+        /// <summary>
+        ///     Gets or sets the number of times this node has transitioned from healthy to failed
+        ///     since startup. Does not decrement on recovery.
+        /// </summary>
+        public int FailureCount { get; set; }
+
+        /// <summary>
+        ///     Gets or sets the message from the most recent failure, or <see langword="null"/> when
+        ///     the node has never failed.
+        /// </summary>
+        public string? LastError { get; set; }
+
+        /// <summary>
+        ///     Gets or sets the UTC timestamp of the most recent failure, or <see langword="null"/>
+        ///     when the node has never failed.
+        /// </summary>
+        public DateTime? LastFailureTime { get; set; }
+    }
+}