docs: complete XML-doc coverage and strip internal tracking IDs from code comments

Resolve all CommentChecker findings across the gateway server, worker, tests,
and .NET client (314 -> 0 real issues): add missing <returns>/<summary>/<param>
on public and test members, convert Stream/interface overrides to <inheritdoc/>,
and remove internal task/issue tracking IDs (SEC-*, IPC-*, WRK-*, GWC-*, TST-*,
Client.Dotnet-*) from shipped code documentation while preserving the design
rationale prose. Shipped comments should not carry internal bookkeeping, and
complete XML docs keep the analyzer/TreatWarningsAsErrors gate and generated API
docs clean. The 6 remaining flags are heuristic false positives (MD5, UTC-4,
capacity-1, near-1601) left intact so real documentation is not corrupted.

Claude-Session: https://claude.ai/code/session_01DMXXvNuPekkkrTEyPNxEkW

src/ZB.MOM.WW.MxGateway.Server/Alarms/GatewayAlarmMonitor.cs

@@ -228,7 +228,7 @@ public sealed class GatewayAlarmMonitor : BackgroundService, IGatewayAlarmServic
                 // Consume mapped MxEvents through the session's single distributor pump (as an
                 // internal, non-counted subscriber) rather than opening a second raw drain of the
                 // worker event channel — a second drain would split events with the dashboard
-                // mirror pump and silently lose Acknowledge/mode-change transitions (GWC-01).
+                // mirror pump and silently lose Acknowledge/mode-change transitions.
                 await foreach (MxEvent mxEvent in _sessionManager
                     .ReadAlarmEventsAsync(session.SessionId, linked.Token)
                     .ConfigureAwait(false))