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/Client/ZB.MOM.WW.OtOpcUa.Client.Shared.Tests/Fakes/FakeEndpointDiscovery.cs

@@ -12,11 +12,7 @@ internal sealed class FakeEndpointDiscovery : IEndpointDiscovery
     /// <summary>Gets the last endpoint URL passed to SelectEndpoint.</summary>
     public string? LastEndpointUrl { get; private set; }
 
-    /// <summary>Selects an endpoint for the given configuration and URL, optionally throwing an exception.</summary>
-    /// <param name="config">The application configuration.</param>
-    /// <param name="endpointUrl">The endpoint URL to select.</param>
-    /// <param name="requestedMode">The requested security mode.</param>
-    /// <returns>The selected endpoint description.</returns>
+    /// <inheritdoc />
     public EndpointDescription SelectEndpoint(ApplicationConfiguration config, string endpointUrl,
         MessageSecurityMode requestedMode)
     {