Auto: abcip-2.6 — AOI input/output handling

AOI-aware browse paths: AOI instances now fan out under directional
sub-folders (Inputs/, Outputs/, InOut/) instead of a flat layout. The
sub-folders only appear when at least one member carries a non-Local
AoiQualifier, so plain UDT tags keep the pre-2.6 flat structure.

- Add AoiQualifier enum (Local / Input / Output / InOut) + new property
  on AbCipStructureMember (defaults to Local).
- L5K parser learns ADD_ON_INSTRUCTION_DEFINITION blocks; PARAMETER
  entries' Usage attribute flows through L5kMember.Usage.
- L5X parser captures the Usage attribute on <Parameter> elements.
- L5kIngest maps Usage strings (Input/Output/InOut) to AoiQualifier;
  null + unknown values map to Local.
- AbCipDriver.DiscoverAsync groups directional members under
  Inputs / Outputs / InOut sub-folders when any member is non-Local.
- Tests for L5K AOI block parsing, L5X Usage capture, ingest mapping
  (both formats), and AOI-vs-plain UDT discovery fan-out.

Closes #234

src/ZB.MOM.WW.OtOpcUa.Driver.AbCip/Import/L5xParser.cs

@@ -218,12 +218,19 @@ public static class L5xParser
                 if (!string.IsNullOrEmpty(raw)) paramDescription = raw.Trim();
             }
 
+            // PR abcip-2.6 — capture the AOI Usage attribute (Input / Output / InOut). RSLogix
+            // also serialises Local AOI tags inside <LocalTags>, but those don't go through this
+            // path — only <Parameters>/<Parameter> entries do — so any Usage value on a parameter
+            // is one of the directional buckets.
+            var usage = paramNode.GetAttribute("Usage", string.Empty);
+
             members.Add(new L5kMember(
                 Name: paramName,
                 DataType: dataType,
                 ArrayDim: arrayDim,
                 ExternalAccess: string.IsNullOrEmpty(externalAccess) ? null : externalAccess,
-                Description: paramDescription));
+                Description: paramDescription,
+                Usage: string.IsNullOrEmpty(usage) ? null : usage));
         }
         return new L5kDataType(name, members);
     }