fix(driver-ablegacy): resolve Medium code-review finding (Driver.AbLegacy-010)

MapLibplctagStatus now casts the int to libplctag.Status and switches on
named enum members (mirroring AbCipStatusMapper) instead of unverified
magic integers. A strongly-typed Status overload is the canonical path;
the int overload delegates to it. MapPcccStatus is retained with a comment
marking it as the reference mapping for future PCCC-STS inspection.
Tests updated to use Status enum members rather than raw integers.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy/AbLegacyStatusMapper.cs

@@ -1,3 +1,5 @@
+using libplctag;
+
 namespace ZB.MOM.WW.OtOpcUa.Driver.AbLegacy;
 
 /// <summary>
@@ -20,28 +22,42 @@ public static class AbLegacyStatusMapper
     public const uint BadTypeMismatch = 0x80730000u;
 
     /// <summary>
-    ///     Map libplctag return/status codes. Same polarity as the AbCip mapper — 0 success,
-    ///     positive pending, negative error families.
+    ///     Map a libplctag return/status code to an OPC UA StatusCode. The integer passed here
+    ///     is <c>(int)Tag.GetStatus()</c> — the underlying value of the libplctag.NET
+    ///     <see cref="Status"/> enum. Delegates to the strongly-typed overload so the mapping
+    ///     stays correct regardless of how the wrapper renumbers native PLCTAG_ERR_* constants
+    ///     in future releases.
     /// </summary>
-    public static uint MapLibplctagStatus(int status)
+    public static uint MapLibplctagStatus(int status) => MapLibplctagStatus((Status)status);
+
+    /// <summary>
+    ///     Map a libplctag.NET <see cref="Status"/> enum value to an OPC UA StatusCode. This is
+    ///     the canonical core; the <c>int</c> overload exists only for the
+    ///     <see cref="IAbLegacyTagRuntime.GetStatus"/> seam which boxes the enum as an int.
+    /// </summary>
+    public static uint MapLibplctagStatus(Status status) => status switch
     {
-        if (status == 0) return Good;
-        if (status > 0) return GoodMoreData;
-        return status switch
-        {
-            -5 => BadTimeout,
-            -7 => BadCommunicationError,
-            -14 => BadNodeIdUnknown,
-            -16 => BadNotWritable,
-            -17 => BadOutOfRange,
-            _ => BadCommunicationError,
-        };
-    }
+        Status.Ok => Good,
+        Status.Pending => GoodMoreData,
+        Status.ErrorTimeout => BadTimeout,
+        Status.ErrorNotFound or Status.ErrorNoMatch or Status.ErrorBadDevice => BadNodeIdUnknown,
+        Status.ErrorNotAllowed => BadNotWritable,
+        Status.ErrorOutOfBounds or Status.ErrorTooLarge or Status.ErrorTooSmall => BadOutOfRange,
+        Status.ErrorUnsupported or Status.ErrorNotImplemented => BadNotSupported,
+        Status.ErrorBadConnection or Status.ErrorBadGateway or Status.ErrorBadReply
+            or Status.ErrorWinsock or Status.ErrorOpen or Status.ErrorClose
+            or Status.ErrorRead or Status.ErrorWrite or Status.ErrorRemoteErr
+            or Status.ErrorPartial or Status.ErrorAbort => BadCommunicationError,
+        _ => BadCommunicationError,
+    };
 
     /// <summary>
     ///     Map a PCCC STS (status) byte. Common codes per AB PCCC reference:
     ///     0x00 = success, 0x10 = illegal command, 0x20 = bad address, 0x30 = protected,
     ///     0x40 = programmer busy, 0x50 = file locked, 0xF0 = extended status follows.
+    ///     libplctag surfaces only its own <see cref="Status"/> enum rather than exposing
+    ///     the raw STS byte, so this method is not wired into the current read/write path.
+    ///     It is retained as the reference mapping for future PCCC-STS inspection.
     /// </summary>
     public static uint MapPcccStatus(byte sts) => sts switch
     {