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/TestSupport/TestHostEnvironmentInitializer.cs

@@ -9,7 +9,7 @@ namespace ZB.MOM.WW.MxGateway.Tests.TestSupport;
 /// <remarks>
 /// Many tests build the full gateway host through <c>GatewayApplication.Build</c> against the dev
 /// <c>appsettings.json</c> (which ships <c>Ldap:Transport=None</c> and other dev-only defaults).
-/// An unset environment resolves to Production, where the SEC-04/06 production guards fail startup
+/// An unset environment resolves to Production, where the production guards fail startup
 /// by design — so those host-building tests would trip the guards. Setting the environment to
 /// Development once, before any test runs, keeps that suite exercising app wiring rather than
 /// production-config validation. Tests that specifically assert production behavior construct
@@ -28,6 +28,10 @@ namespace ZB.MOM.WW.MxGateway.Tests.TestSupport;
 /// </remarks>
 internal static class TestHostEnvironmentInitializer
 {
+    /// <summary>
+    /// Applies the Development environment and isolated self-signed-cert path defaults described
+    /// on this type, run once by the runtime before any test in the assembly executes.
+    /// </summary>
     [ModuleInitializer]
     internal static void SetDevelopmentEnvironmentDefault()
     {