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/Configuration/GatewayConfigurationServiceCollectionExtensions.cs

@@ -15,8 +15,8 @@ public static class GatewayConfigurationServiceCollectionExtensions
     public static IServiceCollection AddGatewayConfiguration(
         this IServiceCollection services, IConfiguration configuration)
     {
-        // GatewayOptionsValidator depends on IHostEnvironment to gate the production-only rules
-        // (SEC-04/06). The real host and the apikey CLI both build through WebApplicationBuilder,
+        // GatewayOptionsValidator depends on IHostEnvironment to gate the production-only rules.
+        // The real host and the apikey CLI both build through WebApplicationBuilder,
         // which registers IHostEnvironment before this call — so TryAdd is a no-op there. Minimal
         // containers (unit tests, tooling) have none; fall back to a non-production environment so
         // the validator still activates and the production guards stay off outside a real
@@ -37,12 +37,16 @@ public static class GatewayConfigurationServiceCollectionExtensions
     /// </summary>
     private sealed class FallbackHostEnvironment : IHostEnvironment
     {
+        /// <summary>Gets or sets the name of the environment; defaults to <see cref="Environments.Development"/>.</summary>
         public string EnvironmentName { get; set; } = Environments.Development;
 
+        /// <summary>Gets or sets the name of the application.</summary>
         public string ApplicationName { get; set; } = typeof(FallbackHostEnvironment).Assembly.GetName().Name ?? "MxGateway";
 
+        /// <summary>Gets or sets the absolute path to the content root directory.</summary>
         public string ContentRootPath { get; set; } = AppContext.BaseDirectory;
 
+        /// <summary>Gets or sets the file provider for the content root.</summary>
         public IFileProvider ContentRootFileProvider { get; set; } = new NullFileProvider();
     }
 }

src/ZB.MOM.WW.MxGateway.Server/Configuration/GatewayOptionsValidator.cs

@@ -470,7 +470,7 @@ public sealed class GatewayOptionsValidator : OptionsValidatorBase<GatewayOption
 
     // The worker-frame (pipe) maximum must stay above the public gRPC cap by the envelope-overhead
     // reserve, otherwise a maximally-sized accepted gRPC payload does not fit one worker frame once
-    // wrapped in a WorkerEnvelope and the outbound write faults the whole session (IPC-03). Fail fast
+    // wrapped in a WorkerEnvelope and the outbound write faults the whole session. Fail fast
     // at startup rather than mid-traffic. Only checked when both knobs are themselves in range so the
     // message is not doubled up with the individual range errors.
     private static void ValidateFrameSizeHeadroom(

src/ZB.MOM.WW.MxGateway.Server/Configuration/SecurityOptions.cs

@@ -2,8 +2,8 @@ namespace ZB.MOM.WW.MxGateway.Server.Configuration;
 
 /// <summary>
 /// Security hot-path options bound from <c>MxGateway:Security</c>. Groups the API-key verification
-/// cache and <c>last_used</c> write-coalescing knobs (SEC-08) with the login and API-key
-/// rate-limiting knobs (SEC-11). Defaults preserve safe, low-overhead behaviour without requiring
+/// cache and <c>last_used</c> write-coalescing knobs with the login and API-key
+/// rate-limiting knobs. Defaults preserve safe, low-overhead behaviour without requiring
 /// operators to configure anything.
 /// </summary>
 public sealed class SecurityOptions

src/ZB.MOM.WW.MxGateway.Server/Configuration/WorkerOptions.cs

@@ -37,8 +37,8 @@ public sealed class WorkerOptions
     /// The maximum worker-frame (pipe) message size in bytes. Must stay at least
     /// <see cref="Workers.WorkerFrameProtocolOptions.EnvelopeOverheadReserveBytes"/> above
     /// <see cref="ProtocolOptions.MaxGrpcMessageBytes"/> so a maximally-sized accepted gRPC payload
-    /// still fits one worker frame (IPC-03); the gateway conveys this value to the worker in the
-    /// handshake (<c>GatewayHello.max_frame_bytes</c>, IPC-02). Default is the 16 MB public gRPC cap
+    /// still fits one worker frame; the gateway conveys this value to the worker in the
+    /// handshake (<c>GatewayHello.max_frame_bytes</c>). Default is the 16 MB public gRPC cap
     /// plus that reserve.
     /// </summary>
     public int MaxMessageBytes { get; init; } =