fix(driver-modbus-cli): resolve Medium code-review finding (Driver.Modbus.Cli-002)

Reject --region Coils combined with any non-boolean --type with a CommandException
that names the constraint: coils carry a single bit, so only --type Bool is valid.
Without this check a write like "--region Coils --type UInt16 --value 42" would
silently coerce to a coil ON with no diagnostic.

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

src/Drivers/Cli/ZB.MOM.WW.OtOpcUa.Driver.Modbus.Cli/Commands/WriteCommand.cs

@@ -60,6 +60,16 @@ public sealed class WriteCommand : ModbusCommandBase
             throw new CliFx.Exceptions.CommandException(
                 $"Region '{Region}' is read-only in the Modbus spec; writes require Coils or HoldingRegisters.");
 
+        // Driver.Modbus.Cli-002: coils are single-bit outputs — only Bool makes sense. A
+        // non-boolean type (e.g. --region Coils --type UInt16) would silently coerce the value
+        // to a boolean via Convert.ToBoolean, landing as ON for any non-zero value, with no
+        // diagnostic. Reject it early so the operator sees a clear error rather than a silent
+        // type-mismatch coerce.
+        if (Region == ModbusRegion.Coils && DataType != ModbusDataType.Bool)
+            throw new CliFx.Exceptions.CommandException(
+                $"Region 'Coils' only supports boolean values (--type Bool). " +
+                $"Type '{DataType}' cannot represent a single-bit coil write.");
+
         var tagName = ReadCommand.SynthesiseTagName(Region, Address, DataType);
         var tag = new ModbusTagDefinition(
             Name: tagName,