feat(server): equipment-tag node writability from Tag.AccessLevel (parity-safe, no migration)

src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/OtOpcUaNodeManager.cs

@@ -633,7 +633,11 @@ public sealed class OtOpcUaNodeManager : CustomNodeManager2
     /// <param name="parentFolderNodeId">The node identifier of the parent folder; null to use the namespace root.</param>
     /// <param name="displayName">The display name of the variable.</param>
     /// <param name="dataType">The OPC UA data type name (e.g., "Boolean", "Int32", "String").</param>
-    public void EnsureVariable(string variableNodeId, string? parentFolderNodeId, string displayName, string dataType)
+    /// <param name="writable">When true the node is created <c>CurrentReadWrite</c> (an authored
+    /// ReadWrite equipment tag); when false it stays <c>CurrentRead</c> (read-only). This task only sets
+    /// the access level — no OnWriteValue handler is attached here (the inbound-write handler is owned
+    /// by a later task).</param>
+    public void EnsureVariable(string variableNodeId, string? parentFolderNodeId, string displayName, string dataType, bool writable)
     {
         ArgumentException.ThrowIfNullOrEmpty(variableNodeId);
         ArgumentException.ThrowIfNullOrEmpty(displayName);
@@ -655,8 +659,10 @@ public sealed class OtOpcUaNodeManager : CustomNodeManager2
                 ReferenceTypeId = ReferenceTypeIds.Organizes,
                 DataType = ResolveBuiltInDataType(dataType),
                 ValueRank = ValueRanks.Scalar,
-                AccessLevel = AccessLevels.CurrentRead,
-                UserAccessLevel = AccessLevels.CurrentRead,
+                // The SDK exposes the flags separately (no CurrentReadWrite composite): ReadWrite is
+                // CurrentRead | CurrentWrite. OR-ing two byte constants promotes to int, so cast back.
+                AccessLevel = writable ? (byte)(AccessLevels.CurrentRead | AccessLevels.CurrentWrite) : AccessLevels.CurrentRead,
+                UserAccessLevel = writable ? (byte)(AccessLevels.CurrentRead | AccessLevels.CurrentWrite) : AccessLevels.CurrentRead,
                 Historizing = false,
                 Value = null,
                 StatusCode = StatusCodes.BadWaitingForInitialData,