Fix E2E test gaps and add comprehensive E2E + parity test suites

- Fix pull consumer fetch: send original stream subject in HMSG (not inbox)
  so NATS client distinguishes data messages from control messages
- Fix MaxAge expiry: add background timer in StreamManager for periodic pruning
- Fix JetStream wire format: Go-compatible anonymous objects with string enums,
  proper offset-based pagination for stream/consumer list APIs
- Add 42 E2E black-box tests (core messaging, auth, TLS, accounts, JetStream)
- Add ~1000 parity tests across all subsystems (gaps closure)
- Update gap inventory docs to reflect implementation status

tests/NATS.Server.Tests/Subscriptions/SubListCtorAndNotificationParityTests.cs

@@ -0,0 +1,46 @@
+using NATS.Server.Subscriptions;
+
+namespace NATS.Server.Tests.Subscriptions;
+
+public class SubListCtorAndNotificationParityTests
+{
+    [Fact]
+    public void Constructor_with_enableCache_false_disables_cache()
+    {
+        var subList = new SubList(enableCache: false);
+
+        subList.CacheEnabled().ShouldBeFalse();
+    }
+
+    [Fact]
+    public void NewSublistNoCache_factory_disables_cache()
+    {
+        var subList = SubList.NewSublistNoCache();
+
+        subList.CacheEnabled().ShouldBeFalse();
+    }
+
+    [Fact]
+    public void RegisterNotification_emits_true_on_first_interest_and_false_on_last_interest()
+    {
+        var subList = new SubList();
+        var notifications = new List<bool>();
+        subList.RegisterNotification(v => notifications.Add(v));
+
+        var sub = new Subscription { Subject = "foo", Sid = "1" };
+        subList.Insert(sub);
+        subList.Remove(sub);
+
+        notifications.ShouldBe([true, false]);
+    }
+
+    [Fact]
+    public void SubjectMatch_alias_helpers_match_existing_behavior()
+    {
+        SubjectMatch.SubjectHasWildcard("foo.*").ShouldBeTrue();
+        SubjectMatch.SubjectHasWildcard("foo.bar").ShouldBeFalse();
+
+        SubjectMatch.IsValidLiteralSubject("foo.bar").ShouldBeTrue();
+        SubjectMatch.IsValidLiteralSubject("foo.*").ShouldBeFalse();
+    }
+}