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.TwinCAT.IntegrationTests/TwinCATXarFixture.cs

@@ -87,14 +87,17 @@ public sealed class TwinCATXarFixture : IAsyncLifetime
         }
     }
 
-    /// <inheritdoc />
+    /// <summary>Initializes the fixture asynchronously (no-op for this fixture).</summary>
+    /// <returns>A completed value task.</returns>
     public ValueTask InitializeAsync() => ValueTask.CompletedTask;
-    /// <inheritdoc />
+    /// <summary>Disposes the fixture asynchronously (no-op for this fixture).</summary>
+    /// <returns>A completed value task.</returns>
     public ValueTask DisposeAsync() => ValueTask.CompletedTask;
 
     /// <summary><c>true</c> when the XAR runtime is reachable + the AmsNetId is set.
     /// Used by the skip attributes to avoid spinning up the fixture for every test
     /// class.</summary>
+    /// <returns><c>true</c> if the runtime is available; otherwise <c>false</c>.</returns>
     public static bool IsRuntimeAvailable()
     {
         if (string.IsNullOrWhiteSpace(Environment.GetEnvironmentVariable(NetIdEnvVar))) return false;