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/Core/ZB.MOM.WW.OtOpcUa.Configuration.Tests/ClusterAuditQueryTests.cs

@@ -51,6 +51,7 @@ public sealed class ClusterAuditQueryTests : IDisposable
 
     /// <summary>Structured rows (ClusterId null, NodeId set) for a node in the cluster are now
     /// visible, alongside the SP-path rows that stamp ClusterId directly.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Surfaces_both_clusterId_rows_and_structured_nodeId_rows()
     {
@@ -77,6 +78,7 @@ public sealed class ClusterAuditQueryTests : IDisposable
     }
 
     /// <summary>An audit row stamped with another cluster's ClusterId never appears.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Does_not_surface_other_cluster_rows()
     {
@@ -91,6 +93,7 @@ public sealed class ClusterAuditQueryTests : IDisposable
     }
 
     /// <summary>Respects the page-size cap, newest first.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Caps_to_page_size_newest_first()
     {