v3 batch1 contracts: RawPaths identity helper + reshaped greenfield entities

Shared-type foundation for Batch 1 fan-out (coordinator contracts commit):
- New Commons/Types/RawPaths.cs — the v3 identity authority (Build/Combine/
  Split/Leaf/TryParent/ValidateSegment, ordinal comparer).
- New entities RawFolder, TagGroup, UnsTagReference.
- Reshape DriverInstance (drop NamespaceId, add nullable RawFolderId),
  Tag (require DeviceId, add nullable TagGroupId, drop DriverInstanceId/
  EquipmentId/FolderPath, keep WriteIdempotent), Equipment (drop
  DriverInstanceId/DeviceId), Device (doc: now universal), ServerCluster
  (nav Namespaces -> RawFolders).
- Delete Namespace, EquipmentImportBatch(+Row), NamespaceKind enum.
- DriverTypeMetadata: drop AllowedNamespaceKinds + NamespaceKindCompatibility.

Solution is intentionally red below the foundation projects until Wave C
integrates. Commons + Core.Abstractions compile green.

src/Core/ZB.MOM.WW.OtOpcUa.Configuration/Entities/Equipment.cs

@@ -17,14 +17,9 @@ public sealed class Equipment
     /// <summary>UUIDv4, IMMUTABLE across all generations of the same EquipmentId. Downstream-consumer join key.</summary>
     public Guid EquipmentUuid { get; set; }
 
-    /// <summary>
-    ///     Optional logical FK to the driver providing data for this equipment.
-    ///     <c>null</c> = VirtualTag-only / driver-less equipment (no field driver).
-    /// </summary>
-    public string? DriverInstanceId { get; set; }
-
-    /// <summary>Optional logical FK to a multi-device driver's device.</summary>
-    public string? DeviceId { get; set; }
+    // v3: equipment no longer binds a driver or device. It references existing raw tags via
+    // UnsTagReference and hosts VirtualTags + ScriptedAlarms. The old DriverInstanceId / DeviceId
+    // binding columns are retired.
 
     /// <summary>Logical FK to <see cref="UnsLine.UnsLineId"/>.</summary>
     public required string UnsLineId { get; set; }