Auto: focas-f1f — figure scaling + diagnostics

Closes #262

src/ZB.MOM.WW.OtOpcUa.Driver.FOCAS/FwlibFocasClient.cs

@@ -318,6 +318,43 @@ internal sealed class FwlibFocasClient : IFocasClient
             new FocasCurrentBlockInfo(TrimAnsiPadding(buf.Data)));
     }
 
+    public Task<IReadOnlyDictionary<string, int>?> GetFigureScalingAsync(CancellationToken cancellationToken)
+    {
+        if (!_connected) return Task.FromResult<IReadOnlyDictionary<string, int>?>(null);
+        // kind=0 → position figures (absolute/relative/machine/distance share the same
+        // increment system per axis). cnc_rdaxisname is deferred — the wire impl keys
+        // by fallback "axis{n}" (1-based), the driver re-keys when it gains axis-name
+        // discovery in a follow-up. Issue #262, plan PR F1-f.
+        short count = 0;
+        var buf = new FwlibNative.IODBAXIS { Data = new byte[FwlibNative.MAX_AXIS * 8] };
+        var ret = FwlibNative.GetFigure(_handle, kind: 0, ref count, ref buf);
+        if (ret != 0) return Task.FromResult<IReadOnlyDictionary<string, int>?>(null);
+        return Task.FromResult<IReadOnlyDictionary<string, int>?>(DecodeFigureScaling(buf.Data, count));
+    }
+
+    /// <summary>
+    ///     Decode the per-axis decimal-place counts from a <c>cnc_getfigure</c> reply
+    ///     buffer. Each axis entry per <c>fwlib32.h</c> is 8 bytes laid out as
+    ///     <c>short dec</c> + <c>short unit</c> + 4 reserved bytes; we read only
+    ///     <c>dec</c>. Keys are 1-based <c>"axis{n}"</c> placeholders — a follow-up
+    ///     PR can rewire to <c>cnc_rdaxisname</c> once that surface lands without
+    ///     changing the cache contract (issue #262).
+    /// </summary>
+    internal static IReadOnlyDictionary<string, int> DecodeFigureScaling(byte[] data, short count)
+    {
+        var clamped = Math.Max((short)0, Math.Min(count, (short)FwlibNative.MAX_AXIS));
+        var result = new Dictionary<string, int>(clamped, StringComparer.OrdinalIgnoreCase);
+        for (var i = 0; i < clamped; i++)
+        {
+            var offset = i * 8;
+            if (offset + 2 > data.Length) break;
+            var dec = BinaryPrimitives.ReadInt16LittleEndian(data.AsSpan(offset, 2));
+            if (dec < 0 || dec > 9) dec = 0;
+            result[$"axis{i + 1}"] = dec;
+        }
+        return result;
+    }
+
     /// <summary>
     ///     Decode + trim a Fanuc ANSI byte buffer. The CNC right-pads block text + opmsg
     ///     bodies with nulls or spaces; trim them so the round-trip through the OPC UA