docs(src): add missing XML docs and strip tracking-ID comments

Sweep of 203 source files resolving CommentChecker findings: add
<summary>/<param>/<returns>/<inheritdoc> where missing, and remove
resolved task/issue tracking markers (Tests-NNN, Worker-NNN, Server-NNN,
Task N) from code comments. Comment/doc-only — no logic changes.
Server+Tests build clean under TreatWarningsAsErrors.

src/ZB.MOM.WW.MxGateway.Tests/Gateway/GatewayEndToEndMultiSubscriberTests.cs

@@ -32,6 +32,7 @@ public sealed class GatewayEndToEndMultiSubscriberTests
     /// Two concurrent StreamEvents RPCs on one session both receive every worker event
     /// the fake worker emits, in order.
     /// </summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task StreamEvents_TwoSubscribers_BothReceiveAllEvents()
     {
@@ -130,6 +131,7 @@ public sealed class GatewayEndToEndMultiSubscriberTests
     /// When one of two subscribers cancels its stream, the other subscriber continues
     /// to receive subsequent events and the session remains usable.
     /// </summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task StreamEvents_OneSubscriberCancels_OtherContinuesReceivingEvents()
     {
@@ -241,6 +243,7 @@ public sealed class GatewayEndToEndMultiSubscriberTests
     /// rejected with gRPC status <see cref="StatusCode.ResourceExhausted"/> while the first
     /// two subscribers keep streaming.
     /// </summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task StreamEvents_ThirdSubscriberWhenCapIsTwo_ReceivesResourceExhausted()
     {
@@ -411,6 +414,9 @@ public sealed class GatewayEndToEndMultiSubscriberTests
         private readonly GatewayMetrics _metrics = new();
         private readonly SessionRegistry _registry = new();
 
+        /// <summary>Initializes a new instance of the <see cref="MultiSubscriberGatewayServiceFixture"/> class.</summary>
+        /// <param name="launcher">Fake worker process launcher backing the session manager.</param>
+        /// <param name="maxEventSubscribersPerSession">Maximum concurrent event subscribers allowed per session.</param>
         public MultiSubscriberGatewayServiceFixture(
             IWorkerProcessLauncher launcher,
             int maxEventSubscribersPerSession = 8)
@@ -446,6 +452,7 @@ public sealed class GatewayEndToEndMultiSubscriberTests
                 new FakeGatewayAlarmService());
         }
 
+        /// <summary>Gets the gateway service under test.</summary>
         public MxAccessGatewayService Service { get; }
 
         /// <summary>
@@ -454,6 +461,10 @@ public sealed class GatewayEndToEndMultiSubscriberTests
         /// bounded by <paramref name="timeout"/>. Fails the test if the count is not reached
         /// within the deadline.
         /// </summary>
+        /// <param name="sessionId">Identifier of the session to poll.</param>
+        /// <param name="n">Target subscriber count to wait for.</param>
+        /// <param name="timeout">Maximum time to wait before failing the test.</param>
+        /// <returns>A task that represents the asynchronous operation.</returns>
         /// <remarks>
         ///     This is the deterministic gate that replaces <c>Task.Delay</c> before Advise
         ///     calls: it proves the production code has registered each subscriber before we
@@ -485,6 +496,8 @@ public sealed class GatewayEndToEndMultiSubscriberTests
             }
         }
 
+        /// <summary>Disposes every session in the registry and releases the fixture's metrics.</summary>
+        /// <returns>A task that represents the asynchronous operation.</returns>
         public async ValueTask DisposeAsync()
         {
             foreach (GatewaySession session in _registry.Snapshot())
@@ -533,8 +546,10 @@ public sealed class GatewayEndToEndMultiSubscriberTests
 
         private readonly FakeWorkerProcess _process = new(ProcessId);
 
+        /// <summary>Gets the task representing the fake worker's running background loop.</summary>
         public Task WorkerTask { get; private set; } = Task.CompletedTask;
 
+        /// <inheritdoc />
         public Task<WorkerProcessHandle> LaunchAsync(
             WorkerProcessLaunchRequest request,
             CancellationToken cancellationToken = default)
@@ -625,6 +640,7 @@ public sealed class GatewayEndToEndMultiSubscriberTests
         private readonly SemaphoreSlim _emitGate = new(0, 64);
         private volatile bool _stopEmitting;
 
+        /// <summary>Gets the task representing the fake worker's running background loop.</summary>
         public Task WorkerTask { get; private set; } = Task.CompletedTask;
 
         /// <summary>Releases the gate so the worker emits one event.</summary>
@@ -640,6 +656,7 @@ public sealed class GatewayEndToEndMultiSubscriberTests
             _emitGate.Release(); // unblock a pending gate wait if any
         }
 
+        /// <inheritdoc />
         public Task<WorkerProcessHandle> LaunchAsync(
             WorkerProcessLaunchRequest request,
             CancellationToken cancellationToken = default)