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/GatewayApplication.cs

@@ -154,8 +154,8 @@ public static class GatewayApplication
         // having pushed the ambient identity before the library's galaxy service runs. That
         // ordering is still required, but it is no longer trusted silently: with
         // Authentication:Mode=ApiKey the provider denies with PermissionDenied and logs the broken
-        // invariant when the identity is absent, instead of resolving to the full hierarchy
-        // (GWC-38). Under Mode=Disabled identity-absent is expected and stays unscoped.
+        // invariant when the identity is absent, instead of resolving to the full hierarchy.
+        // Under Mode=Disabled identity-absent is expected and stays unscoped.
         builder.Services.AddSingleton<ZB.MOM.WW.GalaxyRepository.Grpc.IGalaxyBrowseScopeProvider,
             Security.Authorization.GatewayBrowseScopeProvider>();
 
@@ -164,7 +164,7 @@ public static class GatewayApplication
         // snapshot. GalaxyRepositoryOptions.SnapshotCachePath is init-only, so the default cannot be
         // applied via PostConfigure — supply it as a configuration value (before the bind) when the
         // shipped config leaves it blank. It resolves to the per-OS CommonApplicationData location,
-        // byte-identical to the removed appsettings literal on Windows (SEC-33).
+        // byte-identical to the removed appsettings literal on Windows.
         if (string.IsNullOrWhiteSpace(builder.Configuration["MxGateway:Galaxy:SnapshotCachePath"]))
         {
             builder.Configuration["MxGateway:Galaxy:SnapshotCachePath"] = Path.Combine(
@@ -175,7 +175,7 @@ public static class GatewayApplication
 
         builder.Services.AddZbGalaxyRepository(builder.Configuration, "MxGateway:Galaxy");
 
-        // Validate that persistence has a valid, host-rooted snapshot path (SEC-33).
+        // Validate that persistence has a valid, host-rooted snapshot path.
         builder.Services.AddSingleton<
             Microsoft.Extensions.Options.IValidateOptions<ZB.MOM.WW.GalaxyRepository.GalaxyRepositoryOptions>,
             Configuration.GalaxyRepositoryOptionsValidator>();
@@ -224,7 +224,7 @@ public static class GatewayApplication
     /// </para>
     /// <para>
     /// The location mirrors <c>AuthenticationOptions.SqlitePath</c> so both gateway stores sit
-    /// together, and the mechanism is the one SEC-33 already used for
+    /// together, and the mechanism is the same mechanism already used for
     /// <c>MxGateway:Galaxy:SnapshotCachePath</c> below — same problem, same fix, same file. It also
     /// matches what <c>docs/GatewayConfiguration.md</c> already tells operators to
     /// pass to the <c>secret</c> CLI — an absolute default also removes the CLI/gateway divergence