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/Server/ZB.MOM.WW.OtOpcUa.AdminUI.Tests/InProcessBroadcasterTests.cs

@@ -12,6 +12,7 @@ namespace ZB.MOM.WW.OtOpcUa.AdminUI.Tests;
 /// </summary>
 public sealed class InProcessBroadcasterTests
 {
+    /// <summary>Verifies that Publish raises the Received event for all current subscribers.</summary>
     [Fact]
     public void Publish_raises_Received_for_all_current_subscribers()
     {
@@ -27,6 +28,7 @@ public sealed class InProcessBroadcasterTests
         b.ShouldBe(["evt-1"]);
     }
 
+    /// <summary>Verifies that an unsubscribed handler stops receiving events after removal.</summary>
     [Fact]
     public void Unsubscribed_handler_stops_receiving()
     {
@@ -42,6 +44,7 @@ public sealed class InProcessBroadcasterTests
         received.ShouldBe(["first"]);
     }
 
+    /// <summary>Verifies that Publish with no subscribers does not throw an exception.</summary>
     [Fact]
     public void Publish_with_no_subscribers_does_not_throw()
     {