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.ManagementService/ManagementActor.cs

@@ -59,6 +59,7 @@ public class ManagementActor : ReceiveActor
     /// makes the contract correct ahead of any future worker actors (finding
     /// ManagementService-005).
     /// </summary>
+    /// <returns>A one-for-one Resume strategy with no retry limit.</returns>
     public static SupervisorStrategy CreateSupervisorStrategy() =>
         new OneForOneStrategy(
             maxNrOfRetries: -1,
@@ -85,6 +86,7 @@ public class ManagementActor : ReceiveActor
     /// serializer the HTTP endpoint uses — with cycle-safe settings.
     /// </summary>
     /// <param name="result">The command result object to serialize, or null.</param>
+    /// <returns>The JSON string representation of <paramref name="result"/>, or <c>"null"</c> when null.</returns>
     public static string SerializeResult(object? result) =>
         JsonSerializer.Serialize(result, ResultSerializerOptions);