Auto: opcuaclient-8 — type definition mirroring

Adds an opt-in pass-3 walk of the upstream TypesFolder (i=86) so the OPC UA
Client driver can mirror upstream type definitions into the local address
space. Honours the curation rules from PR-7 (#359). Structural mirror only —
binary-encoding priming via LoadDataTypeSystem is tracked as a follow-up
because that helper was removed from the public ISession surface in
OPCFoundation.NetStandard 1.5.378+.

- IAddressSpaceBuilder.RegisterTypeNode (default no-op for back-compat)
- MirroredTypeNodeInfo + MirroredTypeKind in Core.Abstractions
- OpcUaClientDriverOptions.MirrorTypeDefinitions (default false)
- DiscoverAsync pass-3: FetchTypeTreeAsync + recursive HasSubtype walk per
  branch (ObjectTypes/VariableTypes/DataTypes/ReferenceTypes), best-effort
  IsAbstract read, IncludePaths/ExcludePaths still applied
- 6 new unit tests; all 153 OpcUaClient unit tests pass

Closes #280

src/ZB.MOM.WW.OtOpcUa.Core.Abstractions/IAddressSpaceBuilder.cs

@@ -35,8 +35,77 @@ public interface IAddressSpaceBuilder
     ///     <c>_base</c> equipment-class template).
     /// </summary>
     void AddProperty(string browseName, DriverDataType dataType, object? value);
+
+    /// <summary>
+    ///     Register a type-definition node (ObjectType / VariableType / DataType / ReferenceType)
+    ///     mirrored from an upstream OPC UA server. Optional surface — drivers that don't mirror
+    ///     types simply never call it; address-space builders that don't materialise upstream
+    ///     types can leave the default no-op in place. Default implementation drops the call so
+    ///     adding this method doesn't break existing <see cref="IAddressSpaceBuilder"/>
+    ///     implementations.
+    /// </summary>
+    /// <param name="info">Metadata describing the type-definition node to mirror.</param>
+    /// <remarks>
+    ///     <para>
+    ///         The OPC UA Client driver is the primary caller — it walks <c>i=86</c>
+    ///         (TypesFolder) during <c>DiscoverAsync</c> when
+    ///         <c>OpcUaClientDriverOptions.MirrorTypeDefinitions</c> is set so downstream clients
+    ///         see the upstream type system instead of rendering structured-type values as opaque
+    ///         strings.
+    ///     </para>
+    ///     <para>
+    ///         The default no-op is intentional — most builders (Galaxy, Modbus, FOCAS, S7,
+    ///         TwinCAT, AB-CIP) don't have a meaningful type folder to project into and would
+    ///         otherwise need empty-stub overrides.
+    ///     </para>
+    /// </remarks>
+    void RegisterTypeNode(MirroredTypeNodeInfo info) { /* default: no-op */ }
 }
 
+/// <summary>
+///     Categorises a mirrored type-definition node so the receiving builder can route it into
+///     the right OPC UA standard subtree (<c>ObjectTypesFolder</c>, <c>VariableTypesFolder</c>,
+///     <c>DataTypesFolder</c>, <c>ReferenceTypesFolder</c>) when projecting upstream types into
+///     the local address space.
+/// </summary>
+public enum MirroredTypeKind
+{
+    ObjectType,
+    VariableType,
+    DataType,
+    ReferenceType,
+}
+
+/// <summary>
+///     Metadata describing a single type-definition node mirrored from an upstream OPC UA
+///     server. Built by the OPC UA Client driver during type-mirror pass and consumed by
+///     <see cref="IAddressSpaceBuilder.RegisterTypeNode"/>.
+/// </summary>
+/// <param name="Kind">Type category — drives which standard sub-folder the node lives under.</param>
+/// <param name="UpstreamNodeId">
+///     Stringified upstream NodeId (e.g. <c>"ns=2;i=1234"</c>) — preserves the original identity
+///     so a builder that wants to project the type with a stable cross-namespace reference can do
+///     so. The driver applies any configured namespace remap before stamping this field.
+/// </param>
+/// <param name="BrowseName">OPC UA BrowseName segment from the upstream BrowseName.</param>
+/// <param name="DisplayName">Human-readable display name; falls back to <paramref name="BrowseName"/>.</param>
+/// <param name="SuperTypeNodeId">
+///     Stringified upstream NodeId of the super-type (parent type), or <c>null</c> when the node
+///     sits directly under the root (e.g. <c>BaseObjectType</c>, <c>BaseVariableType</c>). Lets
+///     the builder reconstruct the inheritance chain.
+/// </param>
+/// <param name="IsAbstract">
+///     <c>true</c> when the upstream node has the <c>IsAbstract</c> flag set (Object / Variable /
+///     ReferenceType). DataTypes also expose this — the driver passes it through verbatim.
+/// </param>
+public sealed record MirroredTypeNodeInfo(
+    MirroredTypeKind Kind,
+    string UpstreamNodeId,
+    string BrowseName,
+    string DisplayName,
+    string? SuperTypeNodeId,
+    bool IsAbstract);
+
 /// <summary>Opaque handle for a registered variable. Used by Core for subscription routing.</summary>
 public interface IVariableHandle
 {