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/IMxAccessClient.cs

@@ -0,0 +1,79 @@
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace ZB.MOM.WW.OtOpcUa.Host.Domain
+{
+    /// <summary>
+    ///     Abstraction over MXAccess COM client for tag read/write/subscribe operations.
+    ///     (MXA-001 through MXA-009, OPC-007, OPC-008, OPC-009)
+    /// </summary>
+    public interface IMxAccessClient : IDisposable
+    {
+        /// <summary>
+        ///     Gets the current runtime connectivity state for the bridge.
+        /// </summary>
+        ConnectionState State { get; }
+
+        /// <summary>
+        ///     Gets the number of active runtime subscriptions currently being mirrored into OPC UA.
+        /// </summary>
+        int ActiveSubscriptionCount { get; }
+
+        /// <summary>
+        ///     Gets the number of reconnect cycles attempted since the client was created.
+        /// </summary>
+        int ReconnectCount { get; }
+
+        /// <summary>
+        ///     Occurs when the MXAccess session changes state so the host can update diagnostics and retry logic.
+        /// </summary>
+        event EventHandler<ConnectionStateChangedEventArgs>? ConnectionStateChanged;
+
+        /// <summary>
+        ///     Occurs when a subscribed Galaxy attribute publishes a new runtime value.
+        /// </summary>
+        event Action<string, Vtq>? OnTagValueChanged;
+
+        /// <summary>
+        ///     Opens the MXAccess session required for runtime reads, writes, and subscriptions.
+        /// </summary>
+        /// <param name="ct">A token that cancels the connection attempt.</param>
+        Task ConnectAsync(CancellationToken ct = default);
+
+        /// <summary>
+        ///     Closes the MXAccess session and releases runtime resources.
+        /// </summary>
+        Task DisconnectAsync();
+
+        /// <summary>
+        ///     Starts monitoring a Galaxy attribute so value changes can be pushed to OPC UA subscribers.
+        /// </summary>
+        /// <param name="fullTagReference">The fully qualified MXAccess reference for the target attribute.</param>
+        /// <param name="callback">The callback to invoke when the runtime publishes a new value for the attribute.</param>
+        Task SubscribeAsync(string fullTagReference, Action<string, Vtq> callback);
+
+        /// <summary>
+        ///     Stops monitoring a Galaxy attribute when it is no longer needed by the OPC UA layer.
+        /// </summary>
+        /// <param name="fullTagReference">The fully qualified MXAccess reference for the target attribute.</param>
+        Task UnsubscribeAsync(string fullTagReference);
+
+        /// <summary>
+        ///     Reads the current runtime value for a Galaxy attribute.
+        /// </summary>
+        /// <param name="fullTagReference">The fully qualified MXAccess reference for the target attribute.</param>
+        /// <param name="ct">A token that cancels the read.</param>
+        /// <returns>The value, timestamp, and quality returned by the runtime.</returns>
+        Task<Vtq> ReadAsync(string fullTagReference, CancellationToken ct = default);
+
+        /// <summary>
+        ///     Writes a new runtime value to a writable Galaxy attribute.
+        /// </summary>
+        /// <param name="fullTagReference">The fully qualified MXAccess reference for the target attribute.</param>
+        /// <param name="value">The value to write to the runtime.</param>
+        /// <param name="ct">A token that cancels the write.</param>
+        /// <returns><see langword="true" /> when the write is accepted by the runtime; otherwise, <see langword="false" />.</returns>
+        Task<bool> WriteAsync(string fullTagReference, object value, CancellationToken ct = default);
+    }
+}