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.CLI.Tests/Fakes/FakeOpcUaClientServiceFactory.cs

@@ -17,6 +17,7 @@ public sealed class FakeOpcUaClientServiceFactory : IOpcUaClientServiceFactory
     }
 
     /// <summary>Creates and returns the fake OPC UA client service.</summary>
+    /// <returns>The pre-configured <see cref="FakeOpcUaClientService"/> instance.</returns>
     public IOpcUaClientService Create()
     {
         return _service;