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

tests/ZB.MOM.WW.OtOpcUa.Driver.AbCip.Tests/AbCipUdtMemberTests.cs

@@ -167,6 +167,83 @@ public sealed class AbCipUdtMemberTests
         builder.Variables.ShouldContain(v => v.BrowseName == "EmptyUdt");
     }
 
+    [Fact]
+    public async Task AOI_typed_tag_groups_members_under_directional_subfolders()
+    {
+        // PR abcip-2.6 — when any member carries a non-Local AoiQualifier, the tag is treated
+        // as an AOI instance: Input / Output / InOut members get grouped under sub-folders so
+        // the browse tree mirrors Studio 5000's AOI parameter tabs. Plain UDT tags (every member
+        // Local) keep the pre-2.6 flat layout.
+        var builder = new RecordingBuilder();
+        var drv = new AbCipDriver(new AbCipDriverOptions
+        {
+            Devices = [new AbCipDeviceOptions("ab://10.0.0.5/1,0")],
+            Tags =
+            [
+                new AbCipTagDefinition(
+                    Name: "Valve_001",
+                    DeviceHostAddress: "ab://10.0.0.5/1,0",
+                    TagPath: "Valve_001",
+                    DataType: AbCipDataType.Structure,
+                    Members:
+                    [
+                        new AbCipStructureMember("Cmd", AbCipDataType.Bool, AoiQualifier: AoiQualifier.Input),
+                        new AbCipStructureMember("Status", AbCipDataType.DInt, Writable: false, AoiQualifier: AoiQualifier.Output),
+                        new AbCipStructureMember("Buffer", AbCipDataType.DInt, AoiQualifier: AoiQualifier.InOut),
+                        new AbCipStructureMember("LocalVar", AbCipDataType.DInt, AoiQualifier: AoiQualifier.Local),
+                    ]),
+            ],
+        }, "drv-1");
+        await drv.InitializeAsync("{}", CancellationToken.None);
+
+        await drv.DiscoverAsync(builder, CancellationToken.None);
+
+        // Sub-folders for each directional bucket land in the recorder; the AOI parent folder
+        // and the Local member's lack of a sub-folder confirm only directional members get
+        // bucketed. Folder names are intentionally simple (Inputs / Outputs / InOut) — clients
+        // that browse "Valve_001/Inputs/Cmd" see exactly that path.
+        builder.Folders.Select(f => f.BrowseName).ShouldContain("Valve_001");
+        builder.Folders.Select(f => f.BrowseName).ShouldContain("Inputs");
+        builder.Folders.Select(f => f.BrowseName).ShouldContain("Outputs");
+        builder.Folders.Select(f => f.BrowseName).ShouldContain("InOut");
+
+        // Variables emitted under the right full names — full reference still {Tag}.{Member}
+        // so the read/write paths stay unchanged from the flat-UDT case.
+        var variables = builder.Variables.Select(v => (v.BrowseName, v.Info.FullName)).ToList();
+        variables.ShouldContain(("Cmd", "Valve_001.Cmd"));
+        variables.ShouldContain(("Status", "Valve_001.Status"));
+        variables.ShouldContain(("Buffer", "Valve_001.Buffer"));
+        variables.ShouldContain(("LocalVar", "Valve_001.LocalVar"));
+    }
+
+    [Fact]
+    public async Task Plain_UDT_keeps_flat_layout_when_every_member_is_Local()
+    {
+        // Plain UDTs (no Usage attributes anywhere) stay on the pre-2.6 flat layout — no
+        // Inputs/Outputs/InOut sub-folders should appear since there are no directional members.
+        var builder = new RecordingBuilder();
+        var drv = new AbCipDriver(new AbCipDriverOptions
+        {
+            Devices = [new AbCipDeviceOptions("ab://10.0.0.5/1,0")],
+            Tags =
+            [
+                new AbCipTagDefinition("Tank1", "ab://10.0.0.5/1,0", "Tank1", AbCipDataType.Structure,
+                    Members:
+                    [
+                        new AbCipStructureMember("Level", AbCipDataType.Real),
+                        new AbCipStructureMember("Pressure", AbCipDataType.Real),
+                    ]),
+            ],
+        }, "drv-1");
+        await drv.InitializeAsync("{}", CancellationToken.None);
+
+        await drv.DiscoverAsync(builder, CancellationToken.None);
+
+        builder.Folders.Select(f => f.BrowseName).ShouldNotContain("Inputs");
+        builder.Folders.Select(f => f.BrowseName).ShouldNotContain("Outputs");
+        builder.Folders.Select(f => f.BrowseName).ShouldNotContain("InOut");
+    }
+
     [Fact]
     public async Task UDT_members_mixed_with_flat_tags_coexist()
     {