docs: complete XML doc comments via fixdocs (2757 to 131 findings)

Add missing <returns>/<param>/<summary>/<typeparam> tags and clean up
misused inheritdoc across 481 files so the documented API surface is
complete. Documentation-only (zero code lines changed). The 131 remaining
findings are inheritdoc-style warnings deliberately left to preserve
hand-written implementation rationale (plan-decision notes, race-condition
explanations).

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

@@ -19,6 +19,7 @@ namespace ZB.MOM.WW.OtOpcUa.Driver.Modbus.Cli.Tests;
 public sealed class CommandCancellationTests
 {
     /// <summary>Verifies that probe command gracefully handles cancellation during initialization.</summary>
+    /// <returns>A task that represents the asynchronous test.</returns>
     [Fact]
     public async Task ProbeCommand_swallows_cancellation_during_initialize()
     {
@@ -31,6 +32,7 @@ public sealed class CommandCancellationTests
     }
 
     /// <summary>Verifies that read command gracefully handles cancellation during initialization.</summary>
+    /// <returns>A task that represents the asynchronous test.</returns>
     [Fact]
     public async Task ReadCommand_swallows_cancellation_during_initialize()
     {
@@ -49,6 +51,7 @@ public sealed class CommandCancellationTests
     }
 
     /// <summary>Verifies that write command gracefully handles cancellation during initialization.</summary>
+    /// <returns>A task that represents the asynchronous test.</returns>
     [Fact]
     public async Task WriteCommand_swallows_cancellation_during_initialize()
     {