docs: add missing XML doc comments across gateway, worker, and .NET client

Resolves 1113 documentation-completeness gaps flagged by CommentChecker
(MissingReturns, MissingInheritDoc, InheritDocMisused, MissingDoc,
MissingParam, RedundantInheritDoc) so the API surface is fully documented
and the analyzer scan is clean. Doc comments only; no code changes.

src/ZB.MOM.WW.MxGateway.IntegrationTests/Galaxy/GalaxyRepositoryLiveTests.cs

@@ -7,6 +7,7 @@ namespace ZB.MOM.WW.MxGateway.IntegrationTests.Galaxy;
 public sealed class GalaxyRepositoryLiveTests
 {
     /// <summary>Verifies that the Galaxy Repository can establish a live connection to the ZB database.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [LiveGalaxyRepositoryFact]
     public async Task TestConnection_AgainstZb_Succeeds()
     {
@@ -18,6 +19,7 @@ public sealed class GalaxyRepositoryLiveTests
     }
 
     /// <summary>Verifies that the last deploy time can be retrieved from the ZB database.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [LiveGalaxyRepositoryFact]
     public async Task GetLastDeployTime_AgainstZb_ReturnsTimestamp()
     {
@@ -29,6 +31,7 @@ public sealed class GalaxyRepositoryLiveTests
     }
 
     /// <summary>Verifies that the hierarchy can be retrieved from the ZB database.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [LiveGalaxyRepositoryFact]
     public async Task GetHierarchy_AgainstZb_ReturnsObjects()
     {
@@ -46,6 +49,7 @@ public sealed class GalaxyRepositoryLiveTests
     }
 
     /// <summary>Verifies that object attributes can be retrieved from the ZB database.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [LiveGalaxyRepositoryFact]
     public async Task GetAttributes_AgainstZb_ReturnsAtLeastOneAttribute()
     {