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.Historian.Wonderware.Client.Tests/FakeSidecarServer.cs

@@ -68,6 +68,7 @@ internal sealed class FakeSidecarServer : IAsyncDisposable
     public string PipeName => _pipeName;
 
     /// <summary>Starts the fake sidecar server asynchronously.</summary>
+    /// <returns>A task that completes once the server listener is ready to accept connections.</returns>
     public Task StartAsync()
     {
         _loop = Task.Run(() => RunAsync(_cts.Token));
@@ -194,6 +195,7 @@ internal sealed class FakeSidecarServer : IAsyncDisposable
     }
 
     /// <summary>Releases all resources used by the fake sidecar server.</summary>
+    /// <returns>A value task that represents the asynchronous dispose operation.</returns>
     public async ValueTask DisposeAsync()
     {
         _cts.Cancel();