docs: backfill XML documentation across 756 files

Adds <summary>, <param>, <typeparam>, and <inheritdoc/> tags to public
members surfaced by commentchecker — resolves 5,847 of 5,869 issues
(99.6%) across three /fixdocs passes.

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

@@ -14,6 +14,9 @@ namespace ZB.MOM.WW.OtOpcUa.Driver.Modbus.Tests;
 [Trait("Category", "Unit")]
 public sealed class ModbusExceptionMapperTests
 {
+    /// <summary>Verifies that Modbus exception codes map to informative OPC UA status codes.</summary>
+    /// <param name="code">Modbus exception code.</param>
+    /// <param name="expected">Expected OPC UA status code.</param>
     [Theory]
     [InlineData((byte)0x01, 0x803D0000u)] // Illegal Function → BadNotSupported
     [InlineData((byte)0x02, 0x803C0000u)] // Illegal Data Address → BadOutOfRange
@@ -27,14 +30,25 @@ public sealed class ModbusExceptionMapperTests
     public void MapModbusExceptionToStatus_returns_informative_status(byte code, uint expected)
         => ModbusDriver.MapModbusExceptionToStatus(code).ShouldBe(expected);
 
+    /// <summary>Test transport that raises Modbus exceptions on send.</summary>
     private sealed class ExceptionRaisingTransport(byte exceptionCode) : IModbusTransport
     {
+        /// <summary>Completes immediately.</summary>
+        /// <param name="ct">Cancellation token.</param>
         public Task ConnectAsync(CancellationToken ct) => Task.CompletedTask;
+
+        /// <summary>Returns a failed task with a Modbus exception.</summary>
+        /// <param name="unitId">Modbus unit identifier.</param>
+        /// <param name="pdu">Protocol data unit to send.</param>
+        /// <param name="ct">Cancellation token.</param>
         public Task<byte[]> SendAsync(byte unitId, byte[] pdu, CancellationToken ct)
             => Task.FromException<byte[]>(new ModbusException(pdu[0], exceptionCode, $"fc={pdu[0]} code={exceptionCode}"));
+
+        /// <summary>Completes immediately.</summary>
         public ValueTask DisposeAsync() => ValueTask.CompletedTask;
     }
 
+    /// <summary>Verifies that exception 0x02 surfaces as BadOutOfRange, not BadInternalError.</summary>
     [Fact]
     public async Task Read_surface_exception_02_as_BadOutOfRange_not_BadInternalError()
     {
@@ -48,6 +62,7 @@ public sealed class ModbusExceptionMapperTests
         results[0].StatusCode.ShouldBe(0x803C0000u, "FC03 at an unmapped register must bubble out as BadOutOfRange so operators can spot a bad tag config");
     }
 
+    /// <summary>Verifies that exception 0x04 surfaces as BadDeviceFailure.</summary>
     [Fact]
     public async Task Write_surface_exception_04_as_BadDeviceFailure()
     {
@@ -64,14 +79,25 @@ public sealed class ModbusExceptionMapperTests
         writes[0].StatusCode.ShouldBe(0x808B0000u, "FC06 returning exception 04 (CPU in PROGRAM mode) maps to BadDeviceFailure");
     }
 
+    /// <summary>Test transport that raises non-Modbus exceptions on send.</summary>
     private sealed class NonModbusFailureTransport : IModbusTransport
     {
+        /// <summary>Completes immediately.</summary>
+        /// <param name="ct">Cancellation token.</param>
         public Task ConnectAsync(CancellationToken ct) => Task.CompletedTask;
+
+        /// <summary>Returns a failed task with a non-Modbus exception.</summary>
+        /// <param name="unitId">Modbus unit identifier.</param>
+        /// <param name="pdu">Protocol data unit to send.</param>
+        /// <param name="ct">Cancellation token.</param>
         public Task<byte[]> SendAsync(byte unitId, byte[] pdu, CancellationToken ct)
             => Task.FromException<byte[]>(new EndOfStreamException("socket closed mid-response"));
+
+        /// <summary>Completes immediately.</summary>
         public ValueTask DisposeAsync() => ValueTask.CompletedTask;
     }
 
+    /// <summary>Verifies that non-Modbus transport failures surface as BadCommunicationError.</summary>
     [Fact]
     public async Task Read_non_modbus_failure_maps_to_BadCommunicationError_not_BadInternalError()
     {