Auto: focas-f2a — DIAG: address scheme

New FocasAreaKind.Diagnostic parsed from DIAG:nnn (whole-CNC) and
DIAG:nnn/axis (per-axis), validated against a per-series
FocasCapabilityMatrix.DiagnosticRange table (16i: 0-499; 0i-F family:
0-999; 30i/31i/32i: 0-1023; Power Motion i: 0-255; Unknown: permissive
per existing matrix convention).

IFocasClient gains ReadDiagnosticAsync(diagNumber, axisOrZero, type,
ct) with a default returning BadNotSupported so older transport
variants degrade gracefully. FwlibFocasClient implements it via a new
cnc_rddiag P/Invoke that reuses the IODBPSD struct (same shape as
cnc_rdparam). FocasDriver.ReadAsync dispatches Diagnostic addresses
through the new path; non-Diagnostic kinds keep the existing
ReadAsync route unchanged.

Tests: parser positives (DIAG:1031, DIAG:280/2, case-insensitive,
zero, axis-8) + negatives (malformed, axis>31), capability matrix
boundaries per series, driver-level dispatch verifying axis index
threads through, init-time rejection on out-of-range, and
BadNotSupported fallback when the wire client doesn't override the
default. 266/266 pass in Driver.FOCAS.Tests.

Closes #263

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

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

@@ -154,7 +154,7 @@ public sealed class FocasDriver : IDriver, IReadable, IWritable, ITagDiscovery,
                 var parsed = FocasAddress.TryParse(tag.Address)
                     ?? throw new InvalidOperationException(
                         $"FOCAS tag '{tag.Name}' has invalid Address '{tag.Address}'. " +
-                        $"Expected forms: R100, R100.3, PARAM:1815/0, MACRO:500.");
+                        $"Expected forms: R100, R100.3, PARAM:1815/0, MACRO:500, DIAG:1031, DIAG:280/2.");
                 if (_devices.TryGetValue(tag.DeviceHostAddress, out var device)
                     && FocasCapabilityMatrix.Validate(device.Options.Series, parsed) is { } reason)
                 {
@@ -377,7 +377,10 @@ public sealed class FocasDriver : IDriver, IReadable, IWritable, ITagDiscovery,
                 var client = await EnsureConnectedAsync(device, cancellationToken).ConfigureAwait(false);
                 var parsed = FocasAddress.TryParse(def.Address)
                     ?? throw new InvalidOperationException($"FOCAS tag '{def.Name}' has malformed Address '{def.Address}'.");
-                var (value, status) = await client.ReadAsync(parsed, def.DataType, cancellationToken).ConfigureAwait(false);
+                var (value, status) = parsed.Kind == FocasAreaKind.Diagnostic
+                    ? await client.ReadDiagnosticAsync(
+                        parsed.Number, parsed.BitIndex ?? 0, def.DataType, cancellationToken).ConfigureAwait(false)
+                    : await client.ReadAsync(parsed, def.DataType, cancellationToken).ConfigureAwait(false);
 
                 results[i] = new DataValueSnapshot(value, status, now, now);
                 if (status == FocasStatusMapper.Good)