Fix router frontdoor readiness and route contracts

src/Router/__Libraries/StellaOps.Router.AspNet/StellaRouterOptionsBase.cs

@@ -43,6 +43,12 @@ public class StellaRouterOptionsBase
     /// </summary>
     public int HeartbeatIntervalSeconds { get; set; } = 45;
 
+    /// <summary>
+    /// Maximum interval in seconds between HELLO refreshes on an already-live transport.
+    /// Default: 10 seconds to keep gateway restarts from leaving the frontdoor cold for minutes.
+    /// </summary>
+    public int RegistrationRefreshIntervalSeconds { get; set; } = 10;
+
     /// <summary>
     /// Service trust mode for gateway-enforced authorization semantics.
     /// Default: Hybrid.