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/Monitoring/ConnzParityFieldTests.cs

@@ -1,4 +1,5 @@
 using System.Text.Json;
+using System.Text;
 
 namespace NATS.Server.Tests;
 
@@ -8,14 +9,46 @@ public class ConnzParityFieldTests
     public async Task Connz_includes_identity_tls_and_proxy_parity_fields()
     {
         await using var fx = await MonitoringParityFixture.StartAsync();
-        await fx.ConnectClientAsync("u", "orders.created");
+        var jwt = BuildJwt("UISSUER", ["team:core", "tier:gold"]);
+        await fx.ConnectClientAsync("proxy:edge", "orders.created", jwt);
 
-        var connz = fx.GetConnz("?subs=detail");
+        var connz = fx.GetConnz("?subs=detail&auth=true");
         connz.Conns.ShouldNotBeEmpty();
+        var conn = connz.Conns.Single(c => c.AuthorizedUser == "proxy:edge");
+        conn.Proxy.ShouldNotBeNull();
+        conn.Proxy.Key.ShouldBe("edge");
+        conn.Jwt.ShouldBe(jwt);
+        conn.IssuerKey.ShouldBe("UISSUER");
+        conn.Tags.ShouldContain("team:core");
 
         var json = JsonSerializer.Serialize(connz);
         json.ShouldContain("tls_peer_cert_subject");
-        json.ShouldContain("jwt_issuer_key");
+        json.ShouldContain("tls_peer_certs");
+        json.ShouldContain("issuer_key");
+        json.ShouldContain("\"tags\"");
         json.ShouldContain("proxy");
+        json.ShouldNotContain("jwt_issuer_key");
+    }
+
+    private static string BuildJwt(string issuer, string[] tags)
+    {
+        static string B64Url(string json)
+        {
+            return Convert.ToBase64String(Encoding.UTF8.GetBytes(json))
+                .TrimEnd('=')
+                .Replace('+', '-')
+                .Replace('/', '_');
+        }
+
+        var header = B64Url("{\"alg\":\"none\",\"typ\":\"JWT\"}");
+        var payload = B64Url(JsonSerializer.Serialize(new
+        {
+            iss = issuer,
+            nats = new
+            {
+                tags,
+            },
+        }));
+        return $"{header}.{payload}.eA";
     }
 }