docs: strip task-tracking IDs from code comments and fill missing XML docs

Tracking IDs are review bookkeeping that rots in shipped source; the rationale they tagged is kept. Comment-only change (CommentChecker 458 -> 16 false positives).

src/ZB.MOM.WW.MxGateway.Server/Sessions/GatewaySession.cs

@@ -39,7 +39,7 @@ public sealed class GatewaySession
     private bool _everHadEventSubscriber;
     private SessionEventDistributor? _eventDistributor;
     private bool _eventDistributorStarted;
-    // GWC-34: set under _syncRoot when DisposeAsync nulls _eventDistributor, making the
+    // Set under _syncRoot when DisposeAsync nulls _eventDistributor, making the
     // "one distributor per session, never reset" lifecycle symmetric at both ends. Without it
     // EnsureDistributorCreated reads the null as "not created yet" and builds a REPLACEMENT
     // distributor after teardown — one whose pump can never start (_eventDistributorStarted is a
@@ -163,7 +163,7 @@ public sealed class GatewaySession
     ///     is unit-testable.
     /// </param>
     /// <param name="ownerDashboardTags">
-    ///     Dashboard event-visibility tags inherited from the owning API key (SEC-25). Copied into
+    ///     Dashboard event-visibility tags inherited from the owning API key. Copied into
     ///     the immutable <see cref="Tags"/> set; <see langword="null"/> or empty means untagged.
     ///     The tags come from the owner key, never from the client's wire request, so a client
     ///     cannot label its own session with another tenant's tag.
@@ -265,8 +265,8 @@ public sealed class GatewaySession
     public string? OwnerKeyId { get; }
 
     /// <summary>
-    ///     Gets the dashboard event-visibility tags this session inherited from its owning API key
-    ///     (SEC-25). An empty set means untagged.
+    ///     Gets the dashboard event-visibility tags this session inherited from its owning API key.
+    ///     An empty set means untagged.
     /// </summary>
     /// <remarks>
     ///     Immutable for the session's life — assigned once at construction from the owner key's
@@ -541,7 +541,7 @@ public sealed class GatewaySession
     // concurrent callers (e.g. MarkReady's dashboard mirror and a racing first
     // AttachEventSubscriber) agree on a single distributor and a single start.
     //
-    // GWC-34: after DisposeAsync the null distributor means "gone", not "not built yet", so this
+    // After DisposeAsync the null distributor means "gone", not "not built yet", so this
     // throws instead of constructing a replacement nothing will ever pump. The attach paths already
     // roll back and surface the exception, which is the same SessionNotReady the readiness gates
     // raise — a caller that loses the race to teardown now fails immediately instead of hanging.
@@ -610,7 +610,7 @@ public sealed class GatewaySession
     /// </exception>
     public IEventSubscriberLease AttachInternalEventSubscriber()
     {
-        // Readiness gate, mirroring AttachEventSubscriber (GWC-27). It must run BEFORE
+        // Readiness gate, mirroring AttachEventSubscriber. It must run BEFORE
         // EnsureDistributorCreated: a premature attach would construct the distributor and start
         // its pump against a not-yet-Ready worker, the pump source would throw SessionNotReady,
         // PumpAsync would complete every subscriber with that error and latch _completed, and
@@ -694,7 +694,7 @@ public sealed class GatewaySession
         // These three calls are OUTSIDE _syncRoot to avoid holding it across
         // EnsureDistributorCreated's own lock and StartAsync's Task.Run.
         //
-        // GWC-34: the state check above can be overtaken by a close+dispose before we get here, and
+        // The state check above can be overtaken by a close+dispose before we get here, and
         // EnsureDistributorCreated now says so instead of building an orphan distributor. The
         // dashboard mirror is a best-effort observability attachment on a session that is already
         // gone, so it is abandoned here rather than propagated out of MarkReady — the mirror-started
@@ -1918,7 +1918,7 @@ public sealed class GatewaySession
         {
             distributor = _eventDistributor;
             _eventDistributor = null;
-            // GWC-34: latch the null-out so EnsureDistributorCreated cannot read it as
+            // Latch the null-out so EnsureDistributorCreated cannot read it as
             // "not created yet" and hand a racing attach a distributor that will never pump.
             _eventDistributorDisposed = true;
         }