fix(driver-modbus-cli): resolve Low code-review findings (Driver.Modbus.Cli-003,004,005,006,007,008)

- Driver.Modbus.Cli-003: ModbusCommandBase.ValidateEndpoint rejects
  --port outside 1..65535, non-positive --timeout-ms, and --unit-id
  outside 1..247.
- Driver.Modbus.Cli-004: wrapped SubscribeCommand's OnDataChange handler
  body in a try/catch (warn-and-swallow) and serialised the console
  write through a lock.
- Driver.Modbus.Cli-005: Probe / Read / Write now catch the
  cancellation-during-init OperationCanceledException and print
  'Cancelled.' instead of dumping a stack trace.
- Driver.Modbus.Cli-006: ProbeCommand.ComputeVerdict derives the headline
  from BOTH the driver state and the probe snapshot's OPC UA quality
  class so the headline can't disagree with the wire result.
- Driver.Modbus.Cli-007: docs/Driver.Modbus.Cli.md carries an explicit
  'CLI scope' callout — the address-string grammar is a DriverConfig
  JSON feature; the CLI takes the structured triple only.
- Driver.Modbus.Cli-008: pinned BuildOptions, ValidateEndpoint, the
  region-validation guards, ComputeVerdict, and the cancellation-during-
  initialize paths.

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

tests/Drivers/Cli/ZB.MOM.WW.OtOpcUa.Driver.Modbus.Cli.Tests/CommandCancellationTests.cs

@@ -0,0 +1,66 @@
+using CliFx.Infrastructure;
+using Shouldly;
+using Xunit;
+using ZB.MOM.WW.OtOpcUa.Driver.Modbus.Cli.Commands;
+
+namespace ZB.MOM.WW.OtOpcUa.Driver.Modbus.Cli.Tests;
+
+/// <summary>
+///     Covers Driver.Modbus.Cli-005: <c>probe</c> / <c>read</c> / <c>write</c> must swallow
+///     <see cref="OperationCanceledException"/> so a Ctrl+C during InitializeAsync exits
+///     cleanly instead of dumping a full stack trace through CliFx. <c>SubscribeCommand</c>
+///     already handles this around its <c>Task.Delay</c>; these tests pin the same behaviour
+///     to the connect/read/write commands.
+///     The test pre-cancels the CliFx <see cref="FakeInMemoryConsole"/>; the driver's
+///     <c>ConnectAsync</c> observes the token via <c>Dns.GetHostAddressesAsync</c> and throws
+///     OCE before any socket I/O happens, so the test is hermetic — no real PLC needed.
+/// </summary>
+[Trait("Category", "Unit")]
+public sealed class CommandCancellationTests
+{
+    [Fact]
+    public async Task ProbeCommand_swallows_cancellation_during_initialize()
+    {
+        using var console = new FakeInMemoryConsole();
+        console.RequestCancellation(); // simulate Ctrl+C before ExecuteAsync runs
+
+        var sut = new ProbeCommand { Host = "127.0.0.1" };
+
+        await Should.NotThrowAsync(async () => await sut.ExecuteAsync(console));
+    }
+
+    [Fact]
+    public async Task ReadCommand_swallows_cancellation_during_initialize()
+    {
+        using var console = new FakeInMemoryConsole();
+        console.RequestCancellation();
+
+        var sut = new ReadCommand
+        {
+            Host = "127.0.0.1",
+            Region = ModbusRegion.HoldingRegisters,
+            Address = 0,
+            DataType = ModbusDataType.UInt16,
+        };
+
+        await Should.NotThrowAsync(async () => await sut.ExecuteAsync(console));
+    }
+
+    [Fact]
+    public async Task WriteCommand_swallows_cancellation_during_initialize()
+    {
+        using var console = new FakeInMemoryConsole();
+        console.RequestCancellation();
+
+        var sut = new WriteCommand
+        {
+            Host = "127.0.0.1",
+            Region = ModbusRegion.HoldingRegisters,
+            Address = 0,
+            DataType = ModbusDataType.UInt16,
+            Value = "42",
+        };
+
+        await Should.NotThrowAsync(async () => await sut.ExecuteAsync(console));
+    }
+}