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.Tests/Gateway/Dashboard/HubTokenServiceTests.cs

@@ -145,7 +145,7 @@ public sealed class HubTokenServiceTests
     }
 
     /// <summary>
-    /// The default token lifetime is the short (5-minute) window mandated by SEC-05, not the
+    /// The default token lifetime is the short (5-minute) window, not the
     /// former 30-minute window. Pins the value so a regression that widens the exposure window
     /// of an irrevocable, query-string-carried token is caught in CI.
     /// </summary>