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).

src/Client/ZB.MOM.WW.OtOpcUa.Client.UI/ViewModels/BrowseTreeViewModel.cs

@@ -30,6 +30,7 @@ public class BrowseTreeViewModel : ObservableObject
     /// <summary>
     ///     Loads root nodes by browsing with a null parent.
     /// </summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     public async Task LoadRootsAsync()
     {
         var results = await _service.BrowseAsync();