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/ZB.MOM.WW.OtOpcUa.Driver.S7.Tests/S7DriverReadWriteTests.cs

@@ -14,6 +14,7 @@ namespace ZB.MOM.WW.OtOpcUa.Driver.S7.Tests;
 public sealed class S7DriverReadWriteTests
 {
     /// <summary>Verifies that initialization rejects invalid tag addresses and fails fast.</summary>
+    /// <returns>A task that represents the asynchronous test operation.</returns>
     [Fact]
     public async Task Initialize_rejects_invalid_tag_address_and_fails_fast()
     {
@@ -36,6 +37,7 @@ public sealed class S7DriverReadWriteTests
     }
 
     /// <summary>Verifies that ReadAsync without initialize throws InvalidOperationException.</summary>
+    /// <returns>A task that represents the asynchronous test operation.</returns>
     [Fact]
     public async Task ReadAsync_without_initialize_throws_InvalidOperationException()
     {
@@ -45,6 +47,7 @@ public sealed class S7DriverReadWriteTests
     }
 
     /// <summary>Verifies that WriteAsync without initialize throws InvalidOperationException.</summary>
+    /// <returns>A task that represents the asynchronous test operation.</returns>
     [Fact]
     public async Task WriteAsync_without_initialize_throws_InvalidOperationException()
     {