docs: complete XML doc coverage (returns, summaries, inheritdoc)

Resolve all 622 issues flagged by the enhanced CommentChecker: add missing
<returns> tags (incl. the standard phrasing on non-generic Task methods),
add missing <summary> tags, and replace misused/redundant <inheritdoc/> on
members that override or implement nothing with real documentation.
Documentation-only — no behavior change; solution builds clean.

src/ZB.MOM.WW.ScadaBridge.Host/Health/ActiveNodeGate.cs

@@ -32,11 +32,7 @@ public sealed class ActiveNodeGate : IActiveNodeGate
         _akkaService = akkaService;
     }
 
-    /// <summary>
-    /// <c>true</c> only when this node has joined the cluster (<see cref="MemberStatus.Up"/>)
-    /// AND is the current cluster leader; <c>false</c> in every other state
-    /// (actor system not yet started, node still joining, node is a standby).
-    /// </summary>
+    /// <inheritdoc />
     public bool IsActiveNode
     {
         get