Phase 7 Stream G — Address-space integration (NodeSourceKind + walker emits VirtualTag/ScriptedAlarm)

Per ADR-002, adds the Driver/Virtual/ScriptedAlarm discriminator to DriverAttributeInfo
so the DriverNodeManager's dispatch layer can route Read/Write/Subscribe to the right
runtime subsystem — drivers (unchanged), VirtualTagEngine (Phase 7 Stream B), or
ScriptedAlarmEngine (Phase 7 Stream C).

## Changes
- NodeSourceKind enum added to Core.Abstractions (Driver=0/Virtual=1/ScriptedAlarm=2).
- DriverAttributeInfo gains Source / VirtualTagId / ScriptedAlarmId parameters — all
  default so existing call sites (every driver) compile unchanged.
- EquipmentNamespaceContent gains VirtualTags + ScriptedAlarms optional collections.
- EquipmentNodeWalker emits:
  - Virtual-tag variables — Source=Virtual, VirtualTagId set, Historize flag honored
  - Scripted-alarm variables — Source=ScriptedAlarm, ScriptedAlarmId set, IsAlarm=true
    (triggers node-manager AlarmConditionState materialization)
  - Skips disabled virtual tags + scripted alarms

## Tests — 13/13 in EquipmentNodeWalkerTests (5 new)
- Virtual-tag variables carry Source=Virtual + VirtualTagId + Historize flag
- Scripted-alarm variables carry Source=ScriptedAlarm + IsAlarm=true + Boolean type
- Disabled rows skipped
- Null VirtualTags/ScriptedAlarms collections safe (back-compat for non-Phase-7 callers)
- Driver tags default Source=Driver (ensures no discriminator regression)

## Next
Stream G follow-up: DriverNodeManager dispatch (Read/Write/Subscribe routing by
NodeSourceKind), SealedBootstrap wiring of VirtualTagEngine + ScriptedAlarmEngine,
end-to-end integration test.

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

@@ -33,6 +33,18 @@ namespace ZB.MOM.WW.OtOpcUa.Core.Abstractions;
 ///     (holding registers with level-set values, set-point writes to analog tags) — the
 ///     capability invoker respects this flag when deciding whether to apply Polly retry.
 /// </param>
+/// <param name="Source">
+///     Per ADR-002 — discriminates which runtime subsystem owns this node's dispatch.
+///     Defaults to <see cref="NodeSourceKind.Driver"/> so existing callers are unchanged.
+/// </param>
+/// <param name="VirtualTagId">
+///     Set when <paramref name="Source"/> is <see cref="NodeSourceKind.Virtual"/> — stable
+///     logical id the VirtualTagEngine addresses by. Null otherwise.
+/// </param>
+/// <param name="ScriptedAlarmId">
+///     Set when <paramref name="Source"/> is <see cref="NodeSourceKind.ScriptedAlarm"/> —
+///     stable logical id the ScriptedAlarmEngine addresses by. Null otherwise.
+/// </param>
 public sealed record DriverAttributeInfo(
     string FullName,
     DriverDataType DriverDataType,
@@ -41,4 +53,21 @@ public sealed record DriverAttributeInfo(
     SecurityClassification SecurityClass,
     bool IsHistorized,
     bool IsAlarm = false,
-    bool WriteIdempotent = false);
+    bool WriteIdempotent = false,
+    NodeSourceKind Source = NodeSourceKind.Driver,
+    string? VirtualTagId = null,
+    string? ScriptedAlarmId = null);
+
+/// <summary>
+///     Per ADR-002 — discriminates which runtime subsystem owns this node's Read/Write/
+///     Subscribe dispatch. <c>Driver</c> = a real IDriver capability surface;
+///     <c>Virtual</c> = a Phase 7 <see cref="DriverAttributeInfo"/>.VirtualTagId'd tag
+///     computed by the VirtualTagEngine; <c>ScriptedAlarm</c> = a scripted Part 9 alarm
+///     materialized by the ScriptedAlarmEngine.
+/// </summary>
+public enum NodeSourceKind
+{
+    Driver = 0,
+    Virtual = 1,
+    ScriptedAlarm = 2,
+}