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/Domain/MxErrorCodes.cs

@@ -0,0 +1,76 @@
+namespace ZB.MOM.WW.OtOpcUa.Host.Domain
+{
+    /// <summary>
+    ///     Translates MXAccess error codes (1008, 1012, 1013, etc.) to human-readable messages. (MXA-009)
+    /// </summary>
+    public static class MxErrorCodes
+    {
+        /// <summary>
+        ///     The requested Galaxy attribute reference does not resolve in the runtime.
+        /// </summary>
+        public const int MX_E_InvalidReference = 1008;
+
+        /// <summary>
+        ///     The supplied value does not match the attribute's configured data type.
+        /// </summary>
+        public const int MX_E_WrongDataType = 1012;
+
+        /// <summary>
+        ///     The target attribute cannot be written because it is read-only or protected.
+        /// </summary>
+        public const int MX_E_NotWritable = 1013;
+
+        /// <summary>
+        ///     The runtime did not complete the operation within the configured timeout.
+        /// </summary>
+        public const int MX_E_RequestTimedOut = 1014;
+
+        /// <summary>
+        ///     Communication with the MXAccess runtime failed during the operation.
+        /// </summary>
+        public const int MX_E_CommFailure = 1015;
+
+        /// <summary>
+        ///     The operation was attempted without an active MXAccess session.
+        /// </summary>
+        public const int MX_E_NotConnected = 1016;
+
+        /// <summary>
+        ///     Converts a numeric MXAccess error code into an operator-facing message.
+        /// </summary>
+        /// <param name="errorCode">The MXAccess error code returned by the runtime.</param>
+        /// <returns>A human-readable description of the runtime failure.</returns>
+        public static string GetMessage(int errorCode)
+        {
+            return errorCode switch
+            {
+                1008 => "Invalid reference: the tag address does not exist or is malformed",
+                1012 => "Wrong data type: the value type does not match the attribute's expected type",
+                1013 => "Not writable: the attribute is read-only or locked",
+                1014 => "Request timed out: the operation did not complete within the allowed time",
+                1015 => "Communication failure: lost connection to the runtime",
+                1016 => "Not connected: no active connection to the Galaxy runtime",
+                _ => $"Unknown MXAccess error code: {errorCode}"
+            };
+        }
+
+        /// <summary>
+        ///     Maps an MXAccess error code to the OPC quality state that should be exposed to clients.
+        /// </summary>
+        /// <param name="errorCode">The MXAccess error code returned by the runtime.</param>
+        /// <returns>The quality classification that best represents the runtime failure.</returns>
+        public static Quality MapToQuality(int errorCode)
+        {
+            return errorCode switch
+            {
+                1008 => Quality.BadConfigError,
+                1012 => Quality.BadConfigError,
+                1013 => Quality.BadOutOfService,
+                1014 => Quality.BadCommFailure,
+                1015 => Quality.BadCommFailure,
+                1016 => Quality.BadNotConnected,
+                _ => Quality.Bad
+            };
+        }
+    }
+}